Help with Board Question ( No Word Count), Essay, and Unit Quiz (Note Word Count). APA Format Throughout to include Reference Page. 

Board Question

There have been many major transportation related incidents in recent years involving hazardous materials. If a major incident were to occur in your community, would the current level of emergency response services provided by your community, businesses, and the government be adequate? What programs are currently in place, what actions are being taken, or what actions should be taken by your local emergency response agencies to prepare for such incidents?

Unit Essay

For this assignment, you will compose an essay about the concept of chemical incompatibility including practical information involving two common chemical products.

Choose bleach (a base) and another household chemical product that is an acid and review the product labels. You can access product labels and Safety Data Sheet (SDS) information on the Internet.
Record each product’s chemical formulation.
Review Section 7 of the product SDS and summarize that information as it relates to the chemical incompatibility and storage of the bleach and the other product that you chose.

Use the U.S. EPA Chemical Mixing Compatibility Chart, which can be found by using your favorite search engine, and comment on any chemical incompatibilities associated with the product/chemical(s) that you selected. Include such information as the chemical reactions that could occur if the two products somehow became mixed with one another during an emergency response incident. Also, identify how the chemical properties, uses, and other unique hazards of these two products can affect the tasks and safety of first responders (environmental health and safety/fire service professionals) to an emergency response incident.

Summarize and compare the usefulness of the SDS information and the compatibility chart. Were the two references in agreement, or did you find that the information was contradictory? Include a discussion on how you intend to use chemical incompatibility information to keep your workplace or home safe.

Your response must be at least one page in length. You are required to cite the SDS and the U.S. EPA Chemical Mixing Compatibility Chart in your response. All other sources used, including the textbook, must be referenced. Paraphrased and/or quoted materials must have accompanying citations in APA format. You must cite at least three sources in your response.

Unit Quiz

QUESTION 1

When metallic potassium reacts with water, the hydrogen produced initially __________ .

1.

concentrates around the metal

burns into a powder

dissolves

vaporizes

QUESTION 2

     Firefighters are frequently warned against using _______ on combustible metal fires.

1.

Oxygen

Carbon dioxide

Water

Graphite

QUESTION 3

     A certain metallic phosphide can be used to kill to mice and other pests. The DOT requires identification of this phosphide on a manifest during transport. The proper DOT shipping description is __________.

1.

UN3048, Aluminum phosphide pesticides, 6.1 PG I (Poison)

UN1432, Sodium phosphide, 4.3, (6.1), PG I (Dangerous when Wet) (Poison)

UN2012, Potassium phosphide, 4.3, (6.1), PG I (Dangerous when Wet) (Poison)

UN1397, Aluminum phosphide, 4.3, (6.1), PG I (Dangerous when Wet) (Poison)

QUESTION 4

     Firefighters respond to the scene of an industrial fire in which magnesium was burned. Within a few days of extinguishing the fire, the firefighters begin displaying a fever, cough, nausea, chills, aches/pains and shortness of breath. The firefighters are displaying symptoms of __________.

1.

Influenza

Noro virus

Metal fume fever

Common cold

1

Course Learning Outcomes for Unit III

Upon completion of this unit, students should be able to:

4. Evaluate chemical interactions as they relate to control of potential hazards.
4.1 Determine the chemical reactions and products formed when certain alkali metals and other

metallic substances react with water as related to potential or actual emergency response
incidents.

4.2 Determine the chemical reactions of common acids or bases as related to potential or actual
emergency response incidents.

5. Classify hazardous materials according to Department of Transportation (DOT) classification and
warning systems.
5.1 Identify the hazard class, descriptions, labels, markings, or placards that DOT requires when

transporting corrosive, water reactive and pyrophoric

materials.

5.2 Identify the response actions that are applicable to incidents involving water and air-reactive

materials.

6. Determine strategies for dealing with chemical properties of specific types of hazardous substances.
6.1 Identify the chemical properties, uses, and associated unique hazards of common acids and

bases as related to the tasks and safety of an EHS & FS professional.

Course/Unit
Learning Outcomes

Learning Activity

4.1
Unit III Lesson
Chapter 9 Reading
Unit III Quiz

4.2
Unit III Lesson
Chapter 8 Reading
Unit III Essay

5.1
Unit III Lesson
Chapter 9 Reading
Unit III Quiz

5.2
Unit III Lesson
Chapter 9 Reading
Unit III Quiz

6.1
Unit III Lesson
Chapter 8 Reading
Unit III Essay

6.2
Unit III Lesson
Chapter 9 Reading
Unit III Quiz

Reading Assignment

Chapter 8:
Chemistry of Some Corrosive Materials, pp. 270-304

Chapter 9:
Chemistry of Some Water- and Air-Reactive Substances, pp. 308-342

UNIT III STUDY GUIDE

Chemistry of Acids/Bases and
Water/Air-Reactive Materials

2

UNIT x STUDY GUIDE

Title

Unit Lesson

In this unit, we will study the chemistry of corrosive materials (acids and bases) and water-reactive and air-
reactive (pyrophoric) materials. These are covered in Chapters 8 and 9 of our textbook.

Chapter 8 discusses the nature and properties of acids/bases and differentiates between strong versus weak
acids/bases; concentrated versus diluted acids; and oxidizing versus non-oxidizing acids. The concept of the
pH scale is re-introduced, including the values of some various aqueous solutions. Specific information
regarding the uses, properties, and chemical reactions associated with commonly encountered acids and
bases is provided. The chapter concludes with a discussion of Department of Transportation (DOT),
Environmental Protection Agency (EPA), and Occupational Safety and Health Administration (OSHA)
regulatory requirements regarding these materials. This includes recommended emergency response actions
to incidents involving their unplanned release.

Chapter 9 identifies and discusses the properties and reactions associated with commonly encountered
water-reactive and air-reactive materials. Similar to Chapter 8, DOT and OSHA requirements applicable to the
handling and transportation of these materials are discussed.

Corrosive Materials

When we hear or think of corrosion, we normally associate it with some metals in a deteriorating condition
(rusting, pitting, and breaking). That association is correct as corrosion is defined as the degradation of a
material, which includes metals, plastic, or concrete, due to its reaction with the environment. Visit NASA’s
Corrosion Technology Laboratory website for additional information,
http://corrosion.ksc.nasa.gov/corr_fundamentals.htm. This brings us to the substances or materials that cause
this corrosion phenomenon. Acids and bases are the best examples of corrosive materials.

An acid generates hydrogen ions (H+) when dissolved in water, while a base produces hydroxide ions (OH-)
when dissolved in water. An ion is, “an atom (or group of atoms bound together) with a net electric charge due
to the loss or gain of electrons” (Meyer, 2014, p. 117). Those acids and bases that yield a relatively high
concentration of hydrated hydrogen and hydroxide ions are called strong acids and bases, respectively
(Meyer, 2014). In contrast, acids and bases that do not ionize (break apart) or give up the hydrogen or
hydroxide ions are called weak acids and bases. The ability of the acids and bases to form ions in water is
what makes them corrosive.

An acid participates in a chemical reaction as either an oxidizing acid or a non-oxidizing acid. An oxidizing
acid acts as an oxidizing agent, while a non-oxidizing acid cannot act as an oxidizing agent. Oxidizing acids
include sulfuric, nitric, and perchloric acids; non-oxidizing acids include hydrochloric, hydrofluoric, and
phosphoric acids (Meyer, 2014). Concentrated acid is when it is at its strongest concentration. It can get
diluted with the addition of water.

pH scale: This indicates if an aqueous solution is acidic (pH of 0 to <7.0) or basic (>7 to 14). The pH of an
aqueous solution or mixture can be measured with a meter or with a pH paper. In a chemical laboratory, one
can also measure the pH of a solid (soil/residue samples) by adding deionized water to the solid sample. Note
that the pH of a solution changes with temperature, which is why there are usually differences between on-
site and laboratory pH measurements. Acids act as corrosive materials by reacting with metals, metallic
oxides, metallic carbonates, and skin tissue (see Sections 8.6-A through D in your textbook). Bases act as
corrosive materials by reacting also with metals and skin tissue (see Sections 8.6-E and F in your textbook).

The textbook provides specific information on the acids and bases that are encountered in practice by EHS
and FS professionals. Please note that there are workplace regulations involving acids/bases as well as DOT
requirements when they are being transported.

Regarding incidents involving a release of a corrosive material (after the material has been identified as a
corrosive material), emergency responders should consider the following actions: dilute the material if
appropriate, or neutralize with a solid material. The ERG recommends initial isolation and protective action
zone distances. Incidents that may also come up involving corrosive materials are acid or alkali poisoning
incidents. Poisoning incidents may include corrosive materials that inadvertently get splashed into or on an
individual’s eyes/skin or may even be ingested.

http://corrosion.ksc.nasa.gov/corr_fundamentals.htm

3

UNIT x STUDY GUIDE
Title

Additional note: A corrosivity characteristic is one of the criteria used by the federal EPA and some states to
determine if a waste is considered a hazardous waste. It is usually determined by measuring the pH such that
an aqueous liquid with a pH of less than or equal to 2.0, or equal or greater than 12.5 is considered a
hazardous waste (EPA, 2013). Visit the following EPA website for additional information:
http://www.epa.gov/epawaste/hazard/wastetypes/characteristic.htm.

Water-Reactive and Air-Reactive Materials

We often assume that the use of water is the best way to mitigate incidents involving hazardous materials
because of its diluting and/or cooling effect, not to mention its availability. However, this is not always the
case since there are certain materials that react with water to produce flammable gases that ignite
spontaneously. In some cases, toxic or corrosive products are produced that could endanger lives. When
water reacts with another substance, the process is called hydrolysis (Meyer, 2014).

There are also materials that ignite spontaneously upon exposure to ambient air, typically posing the risk of
fire and explosion (Meyer, 2014). These are known as pyrophoric or air-reactive materials. The inherent
hazard may be initiated by their reactions with the moisture in the air as they are released from containment.
Pyrophoric materials are sometimes stored and processed under oil within enclosed, oxygen free, or dry
atmosphere to avoid hazardous reactions. OSHA requires manufacturers, distributors, and importers to post
GHS flame pictograms on the labels of pyrophoric liquids or solids (Meyer, 2014). In addition, flame and
explosive pictograms must be included on labels of substances or mixtures that upon contact with water form
flammable gases. Many of these compounds are recognizable to us, such as aluminum powder, which is a
component of solid rocket fuels. Pyrophoric characteristics are also exhibited by dust containing titanium,
magnesium, or aluminum.

Alkali Metals: In this unit, the properties of the alkali metals—lithium, sodium, and potassium—are
discussed. If you recall from the periodic table, these metals belong to the same family. In reaction to water,
sodium and potassium produce hydrogen, which bursts spontaneously into flame. Lithium is less reactive, so
the hydrogen generated does not immediately ignite.

Combustible Metals: Other metals that include magnesium, titanium, aluminum, zirconium, and zinc are
typically difficult to ignite when in bulk pieces, but may self-ignite in their divided form without an ignition
source. These metals represent the fuels of Class D fires (Meyer, 2014). The finely divided forms of
combustible metals are regarded as both water-reactive and pyrophoric to varying degrees.

Combustible Dust: A category of material that poses fire or explosion hazard is combustible dust. Although it
is not specifically discussed in the textbook, we need to be aware that incidents involving combustible dust
explosions are more common than we think. Combustible dust is defined by the NFPA as, “any finely divided
solid material that is 420 microns or smaller in diameter (material passing a U.S. No. 40 Standard Sieve) and
presents a fire or explosion hazard when dispersed and ignited in air” (as cited in OSHA, 2014, para. 15). The
conditions necessary for a dust explosion include a sufficiently dense dust cloud, adequate oxygen or air to
support combustion, and an ignition source (Plog, 1988).

Materials that can pose an explosive hazard in dust form can be found in many industries that include, “food
(e.g., candy, sugar, spice, starch, flour, feed), grain, tobacco, plastics, wood, paper, pulp, rubber, furniture,
textiles, pesticides, pharmaceuticals, dyes, coal, metals (e.g., aluminum, chromium, iron, magnesium, and
zinc), and fossil-fuel power generation” (OSHA, n.d., para. 3). For information on regulations, training,
prevention, and mitigation of combustible dust related fires/explosions, check the OSHA website at
https://www.osha.gov/dsg/combustibledust/index.html .

Other Water and/or Air Reactive Materials: These other materials that are discussed in the textbook are
aluminum alkyl compounds and their derivatives, ionic hydrides, metallic phosphides, and metallic carbides.
Certain substances react with water to produce hydrogen chloride vapor or hydrochloric acid, such as
aluminum chloride and phosphorus trichloride. Some substances such as acetic anhydride and acetyl chloride
also produce acetic acid when they react with water.

http://www.epa.gov/epawaste/hazard/wastetypes/characteristic.htm

https://www.osha.gov/dsg/combustibledust/index.html

4

UNIT x STUDY GUIDE

Title
When handling, storing, or transporting these water-reactive and pyrophoric materials, caution must be taken
to avoid their contact with water. OSHA and DOT requirements must be followed to avoid hazardous incidents
involving these materials.

References

Environmental Protection Agency. (2013). Characteristic wastes. Retrieved from
http://www.epa.gov/epawaste/hazard/wastetypes/characteristic.htm

Meyer, E. (2014). Chemistry of hazardous materials (6th ed.). Upper Saddle River, NJ: Pearson.

Occupational Safety and Health Administration. (n.d.). Combustible dust: An explosion hazard. Retrieved from
https://www.osha.gov/dsg/combustibledust/index.html

Occupational Safety and Health Administration. (2014). Combustible dust in industry: Preventing and
mitigating the effects of fire and explosions. Retrieved from
https://www.osha.gov/dts/shib/shib073105.html

Plog, B. (1988) Fundamentals of industrial hygiene (3rd ed.). Chicago, IL: National Safety Council.

Suggested Reading

Solid waste can be hazardous waste if it is specifically listed by the EPA or if it meets any of the established
characteristics of a hazardous waste. This USEPA summary simplifies the hazardous waste identification
process and defines the four characteristics of hazardous waste.

Environmental Protection Agency. (2016). Defining Hazardous Waste: Listed, Characteristic and Mixed
Radiological Waste. Retrieved from https://www.epa.gov/hw/defining-hazardous-waste-listed-
characteristic-and-mixed-radiological-wastes#character

We have discussed hazards associated with different classes of chemicals, but incompatible chemicals can
also have chemical reactions when mixed. These mixtures can react and result in explosions, fires, and the
formation of toxic materials. It is important to gather as much information as possible when storing chemicals
or initiating a chemical reaction. The resource below is a good technical resource for the evaluation of
chemical compatibility.

Environmental Protection Agency. (2017). A method for determining the compatibility of hazardous wastes.
Retrieved from https://cfpub.epa.gov/si/si_public_record_Report.cfm?dirEntryID=46495

https://www.epa.gov/hw/defining-hazardous-waste-listed-characteristic-and-mixed-radiological-wastes#character

https://www.epa.gov/hw/defining-hazardous-waste-listed-characteristic-and-mixed-radiological-wastes#character

https://cfpub.epa.gov/si/si_public_record_Report.cfm?dirEntryID=46495

TABLE 8.12 Shipping Descriptions of Perchloric Acid

fORM Of PERCHLORIC ACID

SHIPPING DESCRIPTION

hloric acid (contains not more than 50% acid by mass) UN1802, Perchloric acid, 8, (5.1), PG II perc

hloric acid (contains more than 50% acid but not more UN1873, Perchloric acid, 5.1, (8), PG I perc 72 % acid by mass) than

10.c OXIDIZING POTENTIAL OF PERCHLORIC ACID
S, d hl . ‘d ·
,-1 t concentrate perc one aci is a powerful oxidizing acid but when it is diluted with nO, . ‘d

‘

water, perchlor~c ac_i reacts a_s a weak ?xidizing agent even when hot. The hot, _concen-

ated perchlonc acid reacts v10lently with organic compounds including cellulosic mate-
~als such as sawdust. In fact, a mixture of perchloric acid and sawdust ignit~s
spontaneously. Every m~asure s~ou~d b~ taken to segregate perchloric acid and orgaruc
compounds, because their combmation is regarded as a fire and explosion hazard.

S.10-D TRANSPORTING PERCHLORIC ACID
When shippers offer perchloric acid for transportation, DOT requires them to identify it
on the accompanying shipping paper in one of the ways shown in Table 8.12, as relevant.
All labeling, marking, and placarding requirements apply.

8.11 HYDROFLUORIC ACID
Hydrogen fluoride is a colorless, fuming liquid or vapor having the chemical formula HF(/)
or HF(g), respectively. Its anhydrous form is typically represented by the acronym AHF.
Solutions of hydrogen fluoride in water are denoted by the chemical formula HF(aq ).

Hydrofluoric acid solutions are used for a variety of purposes. In the household, the

y

are found as components of rust removers and aluminum-cleaning products. In the glass
industry, they are used to polish, etch, and frost glass. In the metallurgical and steel indus-
tries, they are used to pickle brass, copper, and certain steel alloys. In the computer indus-
try, they are used to etch silicon wafers during the manufacture of computer chips. In the
chemical industry, they are used as catalysts and fluorinating agents.

8.11-A PRODUCTION OF HYDROFLUORIC ACID
Hydrofluoric acid is prepared by reacting sulfuric acid with calcium fluoride, a constituent of
the naturally occurring ores fluorspar and fluorite. This production reaction is represented as follows:

CaF2(s) + H 2SO4(conc) CaS04(s) + 2HF(aq)
Calcium fluoride Sulfmic acid Calci um sulfate

Hydrofluoric acid

The concentrated hydrofluoric acid of commerce is a liquid solution containing 70% hydrogen
~~ride ~y mass. A solution containing 49% hydrofluori~ aci~ is also ava~able commercially.

Physical properties of these three forms of hydrofluoric acid are noted m Table 8.13.
fl ~he calcium sulfate is filtered from the resulting mixture, and the solution of hydro-
Uoric acid is boiled until the desired concentration is achieved.

8
‘
11

·8 ILL EFFECTS CAUSED BY EXPOSURE TO HYDROFLUORIC ACID
Altha h · ‘d · k ‘d b h h 1· ‘d andi ug the data in Table 8.1 show that hydrofluoric aci 1s a wea aci , ot t e iqw
the st~ Vapor permeate the skin and produce severe burns t~at heal very slowly. Although
u kin damag · ll . bl as external destruction to the outermost layer, the nder[ . e 1s genera y not1cea e

Ying tissues may also be severely damaged.

Hydrofluoric acid

Chapter 8 Chemistry of Some Corrosive Materials

2S

hypocalcemia The
adverse health condi-
tion associated with
low concentrations of
calcium in the
bloodstream

Anhydrous
hydrogen fluoride

TABLE 8.13

ANHYDROUS HF(/)
(AHF} HF(aq} (49%} HF(aq) (70%)

Melting point -118°F (-84°C) -34°F (-37°() -96oF (-71’C)
Boiling point 67°F (20°C) 224°F (106°C) 151 °F (66’C)
Specific gravity at 70°F (21 °C) 0.97 1.16 1.225
Vapor density (air = 1) 70°F (21 °C) 2.21 1.175 1.76
Vapor pressure at 70°F (21 °C) 776 mmHg 27 mmHg 110 mmHg
Solubility in water Infinitely soluble Infinitely soluble Infinitely soluble

Exposure of the skin to hydrofluoric acid may be fatal because it can cause hypocalce .
during which calcium fluoride precipitates in the body’s tissues and removes calcium frornrn~

,

bloodstream. Calcium is essential for blood clotting and normal muscle and nerve funct’ t e
Its absence in the bloodstream may cause cardiac arrest. To avoid or reduce the impact ins.
the ill effects caused by exposure to hydrofluoric acid, it is essential to follow the first-o~d
· · d a1 mstruct:J.ons note in Figure 8.5.

The pain associated with exposure to hydrofluoric acid may not be iillillediately expe-
rienced, and the visible signs of corrosion may be unapparent until hours after the initial
exposure. At this point, the area of contact may appear blanched and bloodless. Gangrene
may develop if the wound is left unattended. The acid may penetrate into the bones
where decalcification can also occur. Specialized medical treatment following exposure t~
the acid or its fumes is often necessary. This specialized medical treatment includes injec-
tion of calcium-containing substances into burned areas or into the bloodstream.

8.11 -C REACTIONS OF HYDROFLUORIC ACID
WITH SILICON COMPOUNDS

The most distinguishing chemical property of concentrated hydrofluoric acid is its ability
to slowly react with silicon compounds to produce gaseous silicon tetrafluoride. Silicon
compounds are components of ordinary glass. Hydrofluoric acid reacts with them to pro-
duce silicon tetrafluoride. For example, hydrofluoric acid reacts with the sodium silicate
and calcium silicate in glass as follows:

Na2Si03(s) + 6HF(conc) 2NaF(aq) + SiF4(g) + 3H20(l)
Sodium silicate Hydrofluoric acid Sodium fluoride Silicon tetrachloride Wate

r

CaSi03(s) + 6HF(conc) CaF2(s) + SiF4(g) + 3H20(l)
Calcium silicate Hydrofluoric acid Calcium flumide Silicon tetrac hloride Water

Because hydrofluoric acid reacts with the components of glass, the acid is routinely stored and
transported in polyethylene or other hydrofluoric acid-resistant plastic bottles and drums.

8.11 -0 ANHYDROUS HYDROGEN FLUORIDE
dr fl . acid, is Anhydrous hydrogen fluoride (AHF), sometimes called anhydrous hy o uonc ‘de

itself a commercial chemical product. Like its solutions, it is prepared from calcium :u;~us
and sulfuric acid. The physical properties listed in Table 8.13 illustrate that an Y r
hydrogen fluoride readily vaporizes near room temperature. duce

Anhydrous hydrogen fluoride is used mainly in the chemical industry t_o 15).
chlorofluorocarbons, hydrofluorocarbons, and hydrochlorofluorocarbons (Sectwn . ·

0 0
/

In the petroleum refining industry, it is used as an alkylate catalyst for the productJ~sses
high-octane fuels (Section 12.13-E). It is also used during uranium-enrichment proc

292 Chapter 8 Chemistry of Some Corrosive Materials

/. )
I I FIRST AID a

:-.. f
I ‘)

EXPOSURE
FOR HYDROFLUORIC ACID

SEEK IMMEDIATE MEDICAL ATTENTION
CALL 911

SERIOUS TISSUE DAMAGE
WITH DELAYED ONSET

SKIN CONTACT
• IMMEDIATELY (within seconds) proceed to the NEAREST SAFETY

SHOWER and wash affected area FOR 5 MINUTES .
• REMOVE all contaminated CLOTHING while in the shower.
• WITH NITRILE DOUBLE-GLOVED HANDS MASSAGE CALCIUM
GLUCONATE GEL into the affected area. If calcium gluconate gel
is not available, wash area for at least 15 minutes or until
emergency medical assistance arrives .

• REAPPLY CALCIUM GLUCONATE GEL and massage it into affected area EVERY
15 MINUTES until medical assistance arrives or pain disappears.

EYE CONTACT
• IMMEDIATELY (within seconds) proceed TO THE NEAREST EYEWASH

STATION.

• Thoroughly WASH EYES WITH WATER FOR AT LEAST 15 MINUTES
while holding eyelids open.

Ill
• 00 NOT APPLY CALCIUM GLUCONATE GEL TO EYES.

INHALATION
• GET MEDICAL ASSISTANCE by calling 911 ·

y

. . . f • d’ ‘duals who have been exposed to hydrofluoric acid. (Courtesy of the Department of FIGURE 8.5 This poster provides first-aid instructions or in iv_,
Environmental Health & Safety, University of Washington, Seattle, Washmgton.)

(S · . fl · d a gas essential for the production of ection 16.9-D) to prepare uramum hexa uon e,
Ura· ‘d t

lllum fuel for the nuclear power m_ us r::
15

m) of anhydrous hydrogen fluoride is
. . Exposure to even low concentrations (_ PP ays and lung surfaces. Prolonged
U:rit t’ h b hial passagew
el( a Ing to the eyes, skin, and t e ronc ment of pulmonary edema. .

Posure to the vapor may cause the develop h d en fluoride severely corrodes skm
t. As With its solutions contact with anhydrouhs Yk_rogThe tissue corrosion may become
issue d ‘ d beneath t e s m.

an produces severe burns eep Chapter 8 Chemistry of Some Corrosive Materials 293

(g ::–..~) FIRST AID
1 ,w I FOR HYDROFLUORIC ACID

1/~ EXPOSURE

SEEK IMMEDIATE MEDICAL ATTENTION
CALL 911
SERIOUS TISSUE DAMAGE
WITH DELAYED ONSET
SKIN CONTACT
• IMMEDIATELY (within seconds) proceed to the NEAREST SAFETY
SHOWER and wash affected area FOR 5 MINUTES .
• REMOVE all contaminated CLOTHING while in the shower.
• WITH NITRILE DOUBLE-GLOVED HANDS MASSAGE CALCIUM
GLUCONATE GEL into the affected area. If calcium gluconate gel
is not available, wash area for at least 15 minutes or until
emergency medical assistance arrives .
• REAPPLY CALCIUM GLUCONATE GEL and massage it into affected area EVERY
15 MINUTES until medical assistance arrives or pain disappears.

EVE CONTACT
• IMMEDIATELY (within seconds) proceed TO THE NEAREST EYEWASH

STATION.
• Thoroughly WASH EYES WITH WATER FOR AT LEAST 15 MINUTES
while holding eyelids open.

• DO NOT APPLY CALCIUM GLUCONATE GEL TO EYES.

INHALATION
• GET MEDICAL ASSISTANCE by calling 911.

I~

V

FIGURE 8.5 This poster provides first-aid instructions for individuals who have been exposed to hydrofluoric acid. (Courtesy of the Department of
En~ronmental Health & Safety, University of Washington, Seattle, Washington.)

(Section 16.9-D) to prepare uranium hexafluoride, a gas essential for the production of
urallJum fuel for the nuclear power industry. . .
. . Exposure to even low concentrations ( < 15 ppm) of anhydrous hydrogen fluoride 1s Irritating to the k' d th bronchial passageways and lung surfaces. Prolonged ex eyes, s m, an e d

Posure to the vapor may cause the development of pulmonary_ e ema. .
. As With its s I · ‘th anhydrous hydrogen fluoride severely corrodes skm tissu o ut1ons, contact w1 . . b

e and prod b d b neath the skin. The tissue corrosion may ecome uces severe urns eep e
Chapter 8 Chemistry of Some Corrosive Materials 293

Phosphoric
acid

TABLE 8.14
Shipping Descriptions of Hydrofluoric Acid
and Hydrogen Fluoride

HYDROFLUORIC ACID/HYDROGEN FLUORIDE SHIPPING DESCRIPTION

Hydrofluoric acid (contains not more than
60% strength)

UN1790, Hydrofluoric acid solution 8 (6 l)
‘ . • PG 11

Hydrofluoric acid (contains more than
60% strength)

Hydrogen fluoride, anhydrous

UN1790, Hydrofluoric acid solution 8 (6 l)
‘ ‘ • ‘PG I

UN1052, Hydrogen fluoride, anhydrous, 8 16
PG I (Poison – Inhalation Hazard, Zone C) ‘ .l),

evident only hours following the initial exposure with no immediate experience of Pai
Vapor burns to the eyes may result in the formation of lesions or may cause blindness. n.

8 .11 -E WORKPLACE REGULATIONS INVOLVING HYDROGEN FLUORIDE
In the workplace, OSHA requires employers to limit employee exposure to a maxi-
mum hydrogen fluoride vapor concentration of 3 parts per million, averaged over an
8-hour workday.

8 .11-F TRANSPORTING HYDROFLUORIC ACID AND
ANHYDROUS HYDROGEN FLUORIDE

Hydrofluoric acid and anhydrous hydrogen fluoride are transported as liquids. When
shippers offer these compounds for transportation, DOT requires them to provide the
relevant shipping description shown in Table 8.14 on the accompanying shipping paper.
All labeling, marking, and placarding requirements apply.

8.12 PHOSPHORIC ACID
Although there are at least eight mineral acids containing phosphorus, phosphoric acid is
the only one that is commonly encountered. Its chemical formula is H 3PO4 •

Phosphoric acid is most familiar to the general public as a constituent of certain
household cleaning products like Lime-Away. In the chemical industry, it is used as a raw
material for manufacturing organophosphate pesticides (Section 10.20) and a number of
commercially important metallic phosphates. For instance, phosphoric acid is used to
produce superphosphate fertilizer, a synthetic fertilizer consisting of a mixture of calcium
dihydrogen phosphate and calcium sulfate. Phosphoric acid is also used to produce mono-
ammonium phosphate, the dry-chemical fire extinguisher (Section 5.15-B). It is also used
to prepare the surface of steel sheets before painting.

8 .12-A PRODUCTION OF PHOSPHORIC ACID
Phosphoric acid is manufactured from phosphate rock, an ore containing calcium phos·
phate, by either of the following methods:

In the first method, phosphate rock is reacted with sulfuric acid.

Ca3(P04)z(s) + 3H2S04(aq) – 3CaS04(s) + 2H3P04(aq)
Calcium phosphate Sulfuric acid Calci um su lfate Phosphoric acid

The calcium sulfate is filtered from the acid. h
In the second method, elemental phosphorus is produced from phosphate rock; then, t e
phosphorus is burned to fo rm tetraphosphorus decoxide, which is reacted with water.

294 Chapter 8 Chemistry of Some Corrosive Materials

Melting point

soiling point

Specific gravity at 68°F (20° C)

vapor density (air = 1)
vapor pressu re at 68°F (20°C)

solubil ity in water

108°F (42°C)

500°F (260°C)

1.69

3.4

0.0285 mmHg

Very soluble

P4(s) + 502(g) P40 1o(s)
Phosp horus Oxygen Tetraphos phorus decoxide

P40 1o(s) + 6H20(l) 4H3P04(aq)
Tetraphosphorus decox ide Water Phosphoric acid

The reaction between tetraphosphorus decoxide and water is especially violent and
releases considerable heat, 41 kilojoules/mole.

Various grades of phosphoric acid are commercially available. When an aqueous
solution of phosphoric acid is allowed to boil at atmospheric pressure, a syrupy solution
containing about 85% phosphoric acid by mass is produced. This is the concentrated
phosphoric acid of commerce, some physical properties of which are noted in Table 8.15.
In addition, a commercially available food-grade phosphoric acid is used as an ingredient
of certain soft drinks and other food products.

Phosphoric acid exhibits the hazardous features of all corrosive materials: It reacts with
metals, metallic oxides, and metallic carbonates, and it damages skin tissue.

8.12-8 PHOSPHORIC ANHYDRIDE
Tetraphosphorus decoxide, or phosphoric anhydride, is the acidic anhydride of phosphoric
acid. Its chemical formula is P 4 010, This substance has such a strong affinity for water that
it is used industrially as a drying agent.

Because its reaction with water releases 41 kilojoules/mole into the surroundings,
phosphoric anhydride should be segregated from combustible matter to prevent its inad-
vertent ignition. This amount of heat also causes thermal burns when the oxide comes in
contact with the skin.

8.12-C TRANSPORTING PHOSPHORIC ACID AND
PHOSPHORIC ANHYDRIDE

When shippers offer phosphoric acid or phosphoric anhydride for transportation, DOT
requires them to provide the relevant shipping description shown in Table 8.16 on the
accompanying shipping paper. All labeling, marking, and placarding requirements apply.

TABLE 8.16 Shipping Descriptions of Phosphoric Acid
and Phosphoric Anhydride

PHOSPHORIC ACID/PHOSPHORUS ANHYDRIDE
Phosphoric acid, solid

SHIPPING DESCRIPTION

UN1805, Phosphoric acid, solid, 8, PG 111

UN1805, Phosphoric acid solution, 8, PG Ill

UN1807, Phosphorus pentoxide, 8, PG II

Phosphoric acid solutions
Phosphoric anhydride

Phosphoric
anhydride

Chapter 8 Chemistry of Some Corrosive Materials

TABLE 8.15 Physical Properties of Concentrated Phosphoric Acid

Melting point
soiling point
Speci fic gravity at 68°F (20°C)
vapor dens ity (air = 1)
vapor pressure at 68°F (20°C)

solubility in water

Phospho rus

1 os·F (42°cJ
500°F c2Go 0 cJ
1.69
3.4

0.0285 mm Hg
Very soluble

Oxygen Tetraphosphorus decoxide

P40 10(s) + 6H20(/) – 4H3P04(aq)
Telraphosphorus decoxide Water Phosphoric acid

The reaction between tetraphosphorus decoxide and water is especially violent and
releases considerable heat, 41 kilojoules/mole.
Various grades of phosphoric acid are commercially available. When an aqueous
solution of phosphoric acid is allowed to boil at atmospheric pressure, a syrupy solution
containing about 85% phosphoric acid by mass is produced. This is the concentrated
phosphoric acid of commerce, some physical properties of which are noted in Table 8.15.
In addition, a commercially available food-grade phosphoric acid is used as an ingredient
of certain soft drinks and other food products.
Phosphoric acid exhibits the hazardous features of all corrosive materials: It reacts with
metals, metallic oxides, and metallic carbonates, and it damages skin tissue.

8.12-B PHOSPHORIC ANHYDRIDE
Tetraphosphorus decoxide, or phosphoric anhydride, is the acidic anhydride of phosphoric
acid. Its chemical formula is P4 0 10• This substance has such a strong affinity for water that
it is used industrially as a drying agent.

Because its reaction with water releases 41 kilojoules/mole into the surroundings,
phosphoric anhydride should be segregated from combustible matter to prevent its inad-
vertent ignition. This amount of heat also causes thermal burns when the oxide comes in
contact with the skin.

8,12-C TRANSPORTING PHOSPHORIC ACID AND
PHOSPHORIC ANHYDRIDE

When shippers offer phosphoric acid or phosphoric anhydride for transportation, DOT
requires them to provide the relevant shipping description shown in Table 8.16 on the
accompanying shipping paper. All labeling, marking, and placarding requirements apply.

TABLE 8.16

PfiOSPHORIC ACID/PHOSPHORUS ANHYDRIDE SHIPPING DESCRIPTION
Phosphor~ic_a_c,:._:· d.:, s::o:.::li:_:d..:..::::~~.::::_:~::::~==-=—-+-U- N- 18::–:0:-::5:–, ::Ph:–o- s-p:-h-or–:-ic_a_c–:-id-:-,-s-o;:-lid-:-,–:8:–, ::PG~ ll:-1 –

Phosphor-:-i_c~a-c_i..:::dt s:.:o~l:..::u~t~io; n; s~~~~~~~~~~~~~~~~~~~~~~ ~U~N~1~8~0::5–:-,~P~h~o~s~p–:-h~o~r-:–i_c~a~c:-i-::d~s~o~lu~t-:–i_o~n-,:–::8:-,~P~G~ -::-:I_II
Phosph . ‘d one anhydride UN1807, Phosphorus pentox, e, 8, PG II

Phosphoric
anhydride

Chapter 8 Chemistry of Some Corrosive Materials 295

R, &

SOLVED EXERCISE 8.4

Glacial acetic
acid

¢.

What UN marking is em bossed on the bottom of a lined, openhead steel drum used for the transport .
phosphoric acid if the drum was manufacture d in 2010 in the United States by a manufacturer whose re ~tion of
number is M-xxx?

915
lration

Solution: Based on t he information in Table 6.6, an openhead steel drum is identified by the code .. 1A2,, ,
is used to identify Packing Group Ill. The _s pecific_ gravity of phosphoric acid is ~rovided in Table a. 1 s as 7_·6 ‘2″
1 . 7. The test pressure for the steel drum 1s 1 00 kilopasca_ls; 10 1s t~e last two d1g1ts o’. the year in which the~· or
drum was manufactured in the United States; and M-xxx 1s the reg1strat1on number of its manufacturer G’ tee1
combination of information, DOT requ ires the following marking to be embossed on the bottom of a ·st~~~~ this
intended for t he tra nsportation of phosphoric acid : ruin

(]) 1A2/Z1.7/100/10/USA/M-xxx, or UN1A2/Z7.1/100/10/USA/M-xxx

‘ £ . t J

8.13 ACETIC ACID
Acetic acid is the most commonly encountered organic acid. Its chemical formula is
CH 3COOH , or H C2H 30 2 • Each molecule of aceti~ acid is represented by the following
Lewis structure:

H 0
I //

H-C-C
I \

H OH

Acetic acid is the substance responsible for the sour taste and sharp odor of vine·
gar, the common food product containing from 3 % to 6 % acetic acid by volume. It is
used primarily by the chemical industry as a raw material for the synthesis of ethyl
acetate, vinyl acetate, cellulose acetate, and other chemical and pharmaceutical
products .

8.13-A PRODUCTION OF ACETIC ACID
Chemical manufacturers produce acetic acid by a number of methods, the most popular
of which involves the gas-phase combination of methanol and carbon monoxide.

Methano l Carbon monox ide Acetic ac id

When aqueous solutions of acetic acid are cooled to temperatures near 61 °F !1 6°C1′.
a mixture of liquid and solid phases is produced. The liquid phase contains imPt
ties and is recycled or discarded, but the solid phase typically contains more t a~
99% acetic acid by mass. This component is the concentrated acetic acid of coJ1ld
merce, called glacial acetic acid. When encountered, it is generally stored in glass an
plastic containers.

296 Chapter 8 Chemistry of Some Corrosive Materials

TABLE 8.17 Physical Properties of Concentrated Acetic Acid

Melting point

Boil ing point
specific gravity at 68°F (20°()

vapor density (a ir = 1)
vapor pressure at 68°F (20 °C)

Flashpoint
Auto ignition point
Lower flammable lim it
Upper flammable limit

Solubility in water

61°F (17°C)

244°F c11s 0 c)

1.05

2.1

11 mmHg
109°F (43°C)

soo·F (426°()

4% by volume
19.9% by volume
Infinitely soluble

At room temperature, glacial acetic acid is a colorless, pungent liquid. Some of its
important physical properties are noted in Table 8.17. Other varieties are also available
commercially containing from 80 % to 99 % acid by mass.

8.13-B VAPORIZATION OF ACETIC ACID
Concentrated acetic acid releases a vapor, which, when inhaled, is choking and suffocat-
ing and can readily damage the bronchial tract. Exposure to other body tissues, particu-
larly the eyes, results in severe burns.

8.13-C COMBUSTIBLE NATURE OF ACETIC ACID
Co ncentrated acetic acid is an OSHA category 3 flammable liquid (NFPA class II
co mbustible liquid ), but aqueous solutions of acetic acid containing less than 80%
aci d are nonflammable. The complete combustion of acetic acid vapor is represented
as follows:

0
//

CHrC(g ) + 20i(g) – 2COz(g) + 2H20(g) \
OH

Acet ic acid Oxygen Carbon d ioxide Water

Fires involving concentrated acetic acid may be extinguished by diluting the acid
with water.

8,13-D WORKPLACE REGULATIONS INVOLVING ACETIC ACID
the workplace, OSHA requires employers to limit employee exposu re to a maxi-

um acetic acid va por concentration of 10 parts per million , averaged over an
·hour workday.

,13-E TRANSPORTING ACETIC ACID
en shippers offer acetic acid or its solutions for transporta tion, DOT requires them to

‘.0vide the relevant shipping description shown in Table 8.18 on the accompanying ship-
ing Pape r. All labeling, marking, and placarding requirements apply.

Chapter 8 Chemistry of Some Corrosive Materials 297

,

Sodium
hydroxide

Potassium
hydroxide

TABLE 8.18 Shipping Descriptions of Acetic Acid

FORM OF ACETIC ACID SHIPPING DESCRIPTION

Acetic acid (contains more than 10% but not more than UN2790, Acetic acid solution 8 50% acid by mass) ‘ • PG Ill
-:—-.—————————-j——- – –
A c et ic acid solution (contains not less than 50% but not UN2790, Acetic acid solution 8 more than 80% acid by mass) ‘ • PG II
—————————-j– – – —–
A c et i c acid, glacial (contains more than 80% acid by mass) UN2789, Acetic acid, glacial 8 (3) ‘ ‘ • PG II
Acetic acid solution (contains more than 80% acid by mass) UN2789, Acetic acid solution 8 (3) , , , PG11

8.14 SODIUM HYDROXIDE, POTASSIUM HYDROXIDE
AND CALCIUM HYDROXIDE ‘

There are three commercially important corrosive materials that are alkaline: sodi
hydroxide, potassium hydroxide, and calcium hydroxide. Their chemical formulas urn
N a OH , KO H , and Ca (OH )i, respectively. Their physical properties are noted collectiv:;e
in Table 8.19. y

To the layperson, sodium hydroxide is best known as a constituent of consumer prod-
ucts such as Drano and Liquid-Plumr, which are used to unclog drainage pipes, and oven
cleaners like Easy-Off. Sodium hydroxide solutions are also used as industrial cleaners at
car- and truck-washing facilities and garages, and they are used at wastewater facilities to
isolate metallic compounds as water-insoluble metallic hydroxides.

Sodium hydroxide is industrially used in countless applications including the purifi-
cation of petroleum products, the reclaiming of rubber, and the processing of textiles
and paper. The chemical industry uses large amounts of sodium hydroxide as a raw
material during the manufacturing of soap, rayon, cellophane, and numerous commercial
chemical substances.

Potassium hydroxide is used mainly by the chemical industry for the production
of compounds like fertilizers, soft soaps, and pharmaceutical products. It is also the
electrolyte in alkaline storage batteries. Potassium hydroxide was formerly used in
liquid drain cleaners, but at 16 C.F.R. §1500.17, CPSC now bans the manufacture
and sale of cleaners containing potassium hydroxide at a concentration of 10% or
more by weight.

Calcium hydroxide is primarily used as a raw material for the production of mor-
tar, plaster, and cement, but it is also widely used commercially for other purposes.
Emergency responders use it to neutralize acids when they have been unintentionally
released from their containers. A food grade of calcium hydroxide is a component of
some antacids.

TABLE 8.19 Physical Properties of Several Metallic Hydroxides

Melting point

Boiling point

Specific gravity at 68°F (20°C)

Solubility in 100 g of water

SODIUM
HYDROXIDE

s99°F (31 s 0 c)

2534°F (1390°c)

2.13

42 g

POTASSIUM CALCIUM
HYDROXIDE HYDROXIDE

680°F (360°() 1076°F (SBO’C)

24os°F c132o·ci Decomposes

2.04 2.50

107 g 0.18 g

298 Chapter 8 Chemistry of Some Corrosive Materials

S 14 . A PRO D UCTION OF SODIUM HYDROXIDE
. AND POTASSIUM HYDROXIDE
d’ m hydroxide and potassium hydr ‘d

So iu_ urrent through solut’o f odx_1 e are generally manufactured by passing an
eJecrnc_ c I

I
ns O so ium chloride (brine) and potassium chloride, respecnve y.

2N aC l (aq) + 2H20(i) —. 2NaOH(a~/)
Sodi,1111 c hl o ride Water + H2(g) + C l2(g )

Sod ium hydroxide
2KC l(aq)

+

Po1ass ium hydroxide Hydroge n Chlorine
Potassi um chl oride Water

2KOH(aq) +
Hydroge n Chl o,inc

+

om temperature, they are comme · JI ·1 bl • ul
At ro d . rcia Y ava1 a e as flakes pellets sucks gran es, d ncentrate aqueous solutions Th · d · I ‘ • ‘ • ‘ an co d . · e m ustna forms of sodium hydroxide are also as lye an caustic soda wherea th f f • • ·
known ‘ s e arms o potassium hydroXJde are called caustic potash and potash lye.

s.14-B PRODUCTION OF CALCIUM HYDROXIDE
Calcium hydroxide is ind ustrially prepared by reacting calcium oxide and water as
follows:

CaO(s) +
Calciu m oxide

H 20(/) —. Ca(OH)2(s)
Water Calcium hyd roxide

This reaction is called slaking, which gives rise to slaked lime the industrial name of calcium
hydroxide. Calcium oxide is called unslaked lime and quicklime.

8.14-C TRANSPORTING SODIUM HYDROXIDE, POTASSIUM
HYDROXIDE, AND CALCIUM HYDROXIDE

When shippers intend to transport sodium hydroxide, potassium hydroxide, and cal-
cium hydroxide, DOT requires them to provide the relevant shipping description in
Table 8.20 on the accompanying shipping paper. All labeling, marking, and placarding
requirements apply.

DOT regulates the transportation of calcium oxide by air only. Hence, shippers are
obligated to affix a CARGO AIRCRAFT ONLY label in addition to the CORROSIVE
label to its packaging.

When carriers transport 1001 pounds (454 kg) or more of these substances, DOT
requires them to display CORROSIVE placards on the bulk packaging used for shipment
as shown in Figure 8.6.

DOT does not regulate the transportation of calcium hydroxide.

TABLE 8.20 Shipping Descriptions of Some Alkaline Substances

~KALINE SUBSTANCE

~cium oxide (unslaked lime)
Potassium hydroxide, solid

Potassium hydroxide solution
Sodium hydroxide, solid

Sodium hydroxide, solution

SHIPPING DESCRIPTION

UN1910, Calcium oxide, 8, PG Ill

UN1813, Potassium hydroxide, solid, 8, PG II
UN1814, Potassium hydroxide, solution, 8, PG II

UN1823, Sodium hydroxide solid, 8, PG II
UN1824, Sodium hydroxide, solution, 8, PG II

slaking The chemical
process associated with
reacting calcium oxide
(unslaked lime) with
water to form calcium
hydroxide

Chapter 8 Chemistry of Some Corrosive Materials 299

‘

RCRA corrosivity
characteristic For
purposes of RCRA
regulations, the
characteristic of either
liquid waste noted at
40 C.F.R. §261 .22

FIGURE 8 .6 When carriers transport a sodium hydroxide solution, DOT requires them to display the identifi-
cation number 1824 across the center area of the CORROSIVE placards posted on the transport vehicle. DOT
also permits the identification number to be displayed on orange panels or white square-on-point diamonds.
(Courtesy of Bulk Transportation, Inc., Wa lnut, California.)

8.15 RCRA CORROSIVITY CHARACTERISTIC
As first noted in Section 1.3-C, EPA uses the legal authority of RCRA to regulate the
treatment, storage, and disposal of hazardous wastes that exhibit certain characteristics,
one of which is corrosivity.

At 40 C.F.R. §261.22, a waste exhibits the RCRA corrosivity characteristic when it is
either of the following:

An aqueous liquid that has a pH less than or equal to 2 or greater than or equal to 12.5.
A liquid that corrodes steel at a rate greater than 0.25 inches/year (6.25 mm/y) at a
test temperature of 130°F (55°C) using a specified test method.

A waste that exhibits the RCRA corrosivity characteristic is assigned the hazardous waste
number D002.

8.16 WORKPLACE REGULATIONS INVOLVING
CORROSIVE MATERIALS

Among its other responsibilities, OSHA is charged with protecting workers from the ill
effects caused by exposure to corrosive materials. To accomplish this aim, it reqmres
employers to display accident-prevention tags, warning labels, and worded signs that sig-
nal the presence of corrosive materials in the workplace when exposure could damage
property or cause accidental injury to workers. Some examples that relate to identifying
corrosive acids and bases are shown in Figure 8. 7.

300 Chapter 8 Chemistry of Some Corrosive Materials

……….

r

ACID
, QANGEFI’

Wear Gloves
When Handling
Acid or Caustics

·oANGEfL: – .

Caustic

. –
DANGER ‘_,

Wear Gloves and
Rubber Gloves
When Handling

Chemicals

FIGURE 8.7 OSHA requires employers to post worded signs that warn employees of the presence of corrosive
materials in the workplace , OSHA also requires employers at 29 C.F.R. § 1200(h)(3)(iv) to affix accident-
prevention tags or warning labels to their in-plant containers of corrosive materials.

Corrosi ve materials are frequently used in science laboratories and in certain work
environments. In all areas where individuals may be exposed to an injurious corrosive
material, OSHA requires the availability of suitable facilities for quick drenching and
flushing of the eyes and body. An example of a suitable eyewash station and shower is
shown in Figure 8.8.

FIGURE 8 .8 OSHA requires employers at 29
C.F.R. §1910.Sl(c) to provide emergency-use
eyewash units and drench showers in areas
where employees may be exposed to corrosive
materials. Each eyewash unit and shower should
deliver 4 gallons/minute and 20 gallons/minute
of water, respectively, during a 15-minute period.

Chapter 8 Chemistry of Some Corrosive Materials 301

8.17 RESPONDING TO INCIDENTS INVOLVING
A RELEASE OF A CORROSIVE MATERIAL

First-on-the-scene responders may generally identify the presence of a corrosive
at the emergency scene by reference to the NFPA hazard diamond affixed or imp ?1aterial
its storage vessel. Any of the expressions ACID, ALK, or CORR may appear i:~~ed on
tom quadrant of the hazard diagram. They rapidly convey the message that a co/ b?t•
material is contained within the vessel. roSive

At a transportation mishap, emergency responders identify the presence of a corr .
material by observing the following: OSive

The number 8 as a component of a shipping description of a hazardous material ll . . sted
on a sh1ppmg paper
The word CORROSIVE and the number 8 printed on black-and-white labels aff’ d . d ll(e
to containment evices
The word CORROSIVE and the number 8 printed on black-and-white placards displayed
on each side and each end of a transport vehicle containing 1001 pounds (454 kg) or more
of a corrosive material

At an emergency scene involving a corrosive material, the members of the response
crew should conduct their work only while wearing fully encapsulated entry suits with
clear face shields . Because these suits are fabricated from a material through which the
corrosive material cannot penetrate, they protect their wearers from bodily contact with
it. The firefighter shown in Figure 8.9 is wearing an “Entry 1-suit,” which provides suf-
ficient protection to work without the fear of exposure to a corrosive material.

FIGURE 8 .9 This firefighter is wearing a fully encapsulating body suit
for responding to an emergency incident involving the release of a cor-
rosive material into the environment. The chemical nature of the fabric
prevents bodily contact with the corrosive material. Self-contained
breathing apparatus is also essential when responding to emergencies
in which the corrosive material possesses a significant vapor pressure .
(Courtesy of Lakeland Industries, Inc., Ronkonkoma, New York; Image O 2012,
All Rights Reserved.)

302 Chapter 8 Chemistry of Some Corrosive Materials

Althou~h fu!ly enc~psulated entry suits are not themselves designed to protect their
users from inhalmg to~ic vapors or fumes, apparel equipped with self-contained breath-
ing apparatus (S_CBA) is n:iarketed for use _ by_ e_mergency responders. When a bulk quan-
. of a corrosive matenal that has a s1gmficant vapor pressure is encountered, the

utY t SCBA . dd . · · · h responders mus ~se m a 1t10n to wearmg these suits. Examples of acids t at
s ontaneously emit harmful vapors are oleum, fuming nitric acid, concentrated hydro-
hJoric acid, and concentrated acetic acid.

c When they are called to a scene involving the release of a corrosive material, emer-
gency responders should consider the following actions:

1 Dilute the corrosive material with an approximate volume of water equal to at
least 10 times the volume of the material that has been released into the environment.
This is usually an adequate response when relatively small quantities of an acid or base
ha ve spilled o~ leaked. fr~m a co~tainer or storage tank. For instance, suppose that a
I-gallon contamer of hqwd sulfunc acid has inadvertently been spilled on a laboratory
floor and has flowed toward a drain leading to an off-site wastewater treatment plant.
In this situation, dilution of the spilled acid with a copious volume of water lessens the
acid’s corrosive nature.

Special care should be exercised to avoid inhaling the fumes that arise when diluting
fuming sulfuric acid, fuming nitric acid, concentrated hydrochloric acid, and concentrated
acetic acid. The inhalation of these fumes poses the risk of inhalation toxicity because the
fumes can seriously damage the respiratory system.

I Neutralize the corrosive material. This action is recommended when a crew re-
sponds to the environmental release of a relatively large volume of a corrosive material
such as a leak of 10,000 gallons (38 m 3) of an acid from a storage tank or during a
transportation mishap. It generally is impractical to dilute such a large volume of a cor-
rosive material with water, because an even larger volume of water is needed to effectively
reduce its corrosiveness.

A large volume of an acid may be effectively neutralized with solid substances such
as either slaked lime or soda ash, the common names for calcium hydroxide and anhy-
drous sodium carbonate, respectively. As noted in Section 8.3, an acid reacts with a base
to produce a salt of the acid and water; and an acid reacts with a metallic carbonate to
produce a salt of the acid, water, and carbon dioxide.

When slaked lime or soda ash is used to neutralize a spill of hydrochloric acid, the
resulting chemical reactions may be represented by the following equations:

Ca(OH)z(s) + 2HCl(aq) CaClz(aq) + 2H20(l)
Calcium hydroxide Hydrochloric acid Calcium chloride Water

Na2C03(s) + 2HCl(aq) 2NaCl(aq) + C02(g) + H20(l)
Sodium carbonate Hydrochloric ac id Sodium chloride Carbon dioxide Wate r

The use of slaked lime or soda ash results in reducing or eliminating the corrosive nature
of hydrochloric acid by chemically converting it into a group of relatively benign substances.
. W_hen first-on-the-scene emergency responders are called to a transportation mishap
involving the release a bulk shipment of hydrogen chloride or hydrogen fluoride, they
:ust acknowledge that the vapor could cause serious respiratory damage to the team,
r/nsportation personnel and the general public. The Emergency Response Guidebook

commend · 1 · ‘ · · f 1 ·11 f h b tn ulf
1

5 iso at1on and evacuation distances or arge spt s o t ese su stances from
or tr

1
~1 e srnall cylinders or single ton cylinders, multiple ton cylinders, highway tank trucks

ton ttJ and rail tankcars (for hydrogen chloride) and multiple small cylinders or single
yin ers, highway tank trucks or trailers, and rail tankcars (for hydrogen fluoride). 1

~E , merge Pp. 354_355 ncy Response Guidebook (Washington, DC: U.S. Department of Transportation, 2012),

Chapter 8 Chemistry of Some Corrosive Materials 303

r
I SOLVED EXERCISE 8.5

First-on-the-scene responde rs arriving at a domestic transportation _mishap _obse~e· th at a 5000-gallon (lg. 3
overturned tank truck is leaking its liquid contents. The transportation marnfeSt 1nd1 cates that the consign rn I
consists solely of concentrated hydroc hlo ric acid . The hi ghway o n which the truck was traveling is located ap:~nt
imately 250 feet (76.2 m) from th e e dge of a la ke . What procedures should th ese flrS t responders impleme nt ~
save lives , property, and the environment?
Solution: Hydrochloric acid is a corrosive material. Co nsequently, first responders must don an acid-impeo,;0, 1
su it that has been designed to prevent bodily conta ct with a corrosive material. Anoth er hazard assooated .
concentrated hydrochlor ic acid is exposu re to the vapor that_ spontaneo_usly evolves from the liquid . To a::
inhaling this vapor, emergency responders must use se lf-contained breathing apparatus . . .

To save lives, property, and the environment , fi rst -o n-the-scene responders should consider implementation
of the following procedures:

• Use self-conta ined breathing ap paratu s.
Wear special protective clothing.

• Use water fog or foam to reduce toxic ga s f umes in the air.
Dike or dam the spilled material t o pre vent it s spread.
Use slaked lime to neutralize the aci d withi n t he diked area .

8.18 RESPONDING TO INCIDENTS INVOLVING ACID
AND ALKALI POISONING

Paramedic teams are often called to assist in situations in which individuals have inadver-
tently been exposed to corrosive materials. In such incidents, a member of the paramedic
team should immediately contact the American Association of Poison Control Centers.2

In addition, the following actions are appropriate:
Because corrosive materials can irreversibly alter skin tissue at the site of contact,

the affected area should be thoroughly flushed with water.
When a corrosive material has been inadvertently splashed into an individual’s

eyes, pain, swelling, corneal erosion, and blindness can rapidly ensue. Consequently, it
is vital to immediately flush the eyes with a gentle stream of running water for at least
30 minutes (lifting the upper and lower lids occasionally). If the individual is wearing
contact lenses, the eyes should first be irrigated for several minutes, and then, the lenses
should be removed and the eyes again irrigated. The individual should be advised to
promptly contact an ophthalmologist for professional eye treatment.

When a corrosive material has been ingested, the individual may experience difficulty
in swallowing, nausea, intense thirst, shock, difficulty in breathing, and death. Vomiting
should not be induced unless advised by a physician. The stomach wall is relatively tough
and normally capable of withstanding the presence of gastric juices having a pH of less
than 2. Vomiting should not be induced, because the individual’s stomach contents could
inadvertently be channeled into the bronchial tract, where they could cause serious damage.
However, paramedics may attempt to neutralize the individual’s stomach contents. Milk 0(
magnesia, a white suspension of magnesium hydroxide in water, may be used to neutraliz_e
acids. A popular brand is Phillips’ Milk of Magnesia, which is often found in home medt·
cine cabinets. Acidic foods such as vinegar and citrus fruit juices may be used to neutralize
bases. To ensure that the corrosive material has been completely neutralized, the individual
should consume a volume of the neutralizing agent at least equal to the amount ingeSted.

2The America_n Association of Poison Control Centers can be accessed by telephone at (800) 222-1 222, lt is
~ssenttally a library staffed by no~edical personnel. Be prepared to give the name of the poisonous producr
involved ‘.nth~ emergency and any information provided on the label. The poison hotline may also be conrac ted
when an ind1v1dual overdoses on medication.

304 Chapter 8 Chemistry of Some Corrosive Materials

• • ,

I

r ! ‘..

‘

CHAPTER 9
• \ i

I
‘

·A~Y.h j

Courtesy of Tyro Fire Protection Products,
Lansdale, Pennsylvania.

air-reactive substance
(pyrophoric substance), p. 309
alloy, p. 313
aluminum alkyl, p. 324
amalgam, p. 313
chlorosilane, p. 334
combustible metal, p. 316
dangerous-when-wet
material, p.

310

ductile, p. 321

Chemistry of So me Water-
and Air-Reactive Substances

flammable solid, p. 310
galvanize, p. 323
hydrolysis, p. 309
ionic hydride, p. 328
malleable, p. 320
metal fume fever, p. 318
metallic carbide, p. 331
metallic phosphide, p. 330
metallic superoxide (metallic
hyperoxide), p. 314

silane, p. 334
spontaneously combustible
material, p. 310
thermite, p. 321
thermite reaction, p. 321
water-reactive substance, p. 309
Ziegler-Natta catalyst, p. 325

Associate the physical and health hazards of the water- and air-reactive materials
noted in this chapter with the information provided by their hazard diamonds
and GHS pictograms.
Identify the industries that use the water- and air-reactive materials noted in
this chapter.
Identify the labels, markings, and placards that DOT requires on packaging
of water- and air-reactive materials and the transport vehicles used for their
shipment.
Identify the response actions to be executed when water- and air-reactive materials
are released from their packaging into the environment.

308

I

rhe members of several classes of substances are likely to pose special problems w.he~ they are_ encou?tered by eme_rgency responders. Two such classes are water-reacuve and a1r-react1ve (pyrophonc) substances.
• A water-reactive substance is an element or compound that reacts with water to

produce either flammable gases that ignite spontaneously or toxic or corrosive com-
pounds chat ?1ay endanger one’s health upon exposure. ‘

• An air-reactive substance (pyrophoric substance) is an element or compound that
ignites spont~neousl~ upon _exposure to the oxygen or moisture in the ambient air,
rypically posmg the nsk of fire and explosion.

When a substa?ce is water- or air-reactive, the use of water as a fire extinguisher is
not only inappropriate, but could be dangerous. Fires involving these substances usually
must be fought using special fire extinguishers, not water. As we progress through this
chapter, these special extinguishers will be noted.

9.1 WATER- AND AIR-REACTIVE SUBSTANCES
When water reacts with another substance, the chemical phenomenon is called hydrolysis.
In chemistry, this process is represented by the following general equation:

A + H20(l) —–+ C + D
Here, A represents a water-reactive substance, and C and D are the substances produced
when A reacts with water. Exposure to the hydrolysis products can be harmful, because C
and D may be flammable, corrosive, or toxic. The application of water should always be
avoided during emergency response actions at which A is present, especially when either
C or D is a flammable or toxic substance.

Consider the metals displayed in Figure 9.1. They react with water, including atmos-
pheric moisture, to produce flammable hydrogen; others are so chemically reactive that
they spontaneously ignite in air without exposure to an ignition source. As the hydrogen
forms, it absorbs the heat of reaction, self-ignites, and triggers the combustion of the met-
als. These metals constitute the fuels of class D fires.

As noted, the hydrolysis of a substance may result in the formation of a solution that
is corrosive. For example, ferric chloride reacts with water to produce ferric hydroxide
and hydrochloric acid.

FeCl3(aq) + 3Hz0(/) —–+ Fe(OH)}(s) + 3HCl( aq)
Ferric chloride Water Ferric hydroxide Hydrochloric acid

1A 2A 3A 4A 5A

4 5 6 7

Be B C N

12 13 14 15

Mg 68 78 18 28
Al Si p

3B 48 58

20 21 22 23 24 25 26 27 28 29 30 31 32 33

Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As

38 39 40 41 42 43 44 45 46 47 48 49 50 51

Sr V Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb

water-reactive
substance A substance
that, by its chemical
reaction with water, is
likely to become spon-
taneously flammable,
emit flammable or toxic
gases, or generate suf-
ficient heat to self-
ignite or cause the
ignition of nearby com-
bustible materials

air-reactive substance
(pyrophoric substance)

A substance that
ignites spontaneously
upon exposure to
the air

hydrolysis • The chemi-
cal reaction between a
substance and water

Ferric chloride

6A 7A BA

8 9 10

0 F Ne

16 17 18

s Cl Ar
34 35 36
Se Br Kr

52 53 54
Te I Xe

FIGURE 9. 1 The symbols of the metals whose background shading are blue and yellow, respectively, represent the alkali metals and combus-
tible metals noted in this chapter. Their finely divided physical forms may self-ignite upon exposure to air.

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

309

dangerous-when-wet
material For purposes
of DOT regulations, a
material that by inter-
action with water is
likely to become spon-
taneously flammable or
to release a flammable
or toxic gas or vapor
at a rate greater than
28 in. 3/lb (1 L/kg) per
hour when subjected
to prescribed test
procedures

spontaneously combus-
tible material For pur-
poses of DOT
regulations, either a
pyrophoric material or
a self-heating material

flammable solid For
purposes of DOT regu-
lations, any of the fol-
lowing types of
materials: wetted
explosives; thermally
unstable compounds
that can undergo a
strongly exothermic
decomposition even
without the participa-
tion of atmospheric
oxygen; and readily
combustible solids

Ferric hydroxide is insoluble; hence, the character of the solution is pr .
acid. For this reason, aqueous solutions of ferric chloride are corrosive. R~vi~ed by th
volumes of the_m are tr~nsported in tank truc~s to ~a.cili~ies that treat water a:tely lar;
ter. DOT reqmres earners to display the UN 1dent1ficat10n number 2582 on Wast~
I oran L es, across the center of CORROSIVE placards, or on white square-on-point di ge Pan.

posed on each side and each end of the trucks . alllo%
When the hydrolysis of a substance produces a toxic vapor, emergency respo d

to be especially cautious to avoid inhaling it. Some dangerous-when-wet substan n ers need
sufficient toxic vapor when they undergo hydrolysis that they pose an inhalatio:~s Prodllce
to individuals who are located 0.3 to 6.0 miles (0.5-10 km) downwind. A list of t~althrisk
stances is provided in DOT’s Emergency Response Guidebook, and several repr ese 8Ub.
dangerous-when-wet materials are reproduced in Table 9.1. When these substesentative
involved in emergencies, first-on-the scene responders should give special attentio:~ces are
and select appropriate actions to reduce or eliminate the potential for their inhalatio O thein

n.
9 .1-A IDENTIFYING AIR-REACTIVE (PYROPHORIC) SUBSTANCES
Pyrophoric substances pose the risk of fire and explosion because they ignite rapidly wh
exposed to at~osphe_ric oxygen. This inherent hazard may be initiated ‘:”hen they react wi:~
the atmospheric moisture encountered as they are released from their containers. l’h
su~stances not only burn spontaneously, but their fires are so exothermic that they pos:se
umque challenge to firefighting efforts. To prevent their premature ignition, pyrophort
su_bs~ances sometimes are stored and processed under oil or other nonaqueous liquids

0
~

within enclosed, oxygen-free, dry atmospheres. To avoid their premature ignition during
storage and transportation, manufacturers seal them hermetically in airtight containers.

Fortunately, few pyrophoric substances are used as commercial chemical products
and they are almost always stored in nonbulk amounts. OSHA requires their manufactur’. ‘
ers, distributors, and importers to post the GHS flame pictogram on the labels of pyro-
phoric liquids or solids, and the flame and explosive pictograms on t_he labels of substances
or mixtures that form flammable gases upon contact with water.

9.1-B TRANSPORTING WATER-REACTIVE SUBSTANCES
When water-reactive substances are transported, DOT regulates their transportation as
dangerous-when-wet materials, spontaneously combustible materials, flammable solids,
or corrosive materials. Individual water-reactive substances may be members of one or
more of these hazard classes. DOT requires their shippers and carriers to comply with
relevant labeling, marking, and placarding requirements.

SOLVED EXERCISE 9.1

310

What information regarding water reactivity is immediately conveyed to responding firefighters by a hazard dia-
mond displayed on the exterior wall of a burning shed?
Solution: Information regarding the water reactivity of a substance is conveyed on a hazard diamond in two
ways . As first noted in Section 1. 11 , a substance ‘s relative degree of the health, fire, and instability hazards 15
conveyed through numbers in the three topmost quadrants of a diamond . The relative degree of water reactivity
is conveyed by the number that appears in the rightmost yellow quadrant, as follows :

“3” means that the substance reacts explosively with water.
“2” means that the substance may react violently with water or may form potentially explosive mixtures with water.
“1” means that the substance may react with water with some release of energy, but not violently.
“O” means that the substance does not react with water.

In addition, the prese_nce o’. a ~apital letter W with a line through i~s center ry,,J) in t~e bottommo~t qua~~:~t
of the diamond serves to signal f1ref1ghters that they should avoid applying water when f1ght1ng a fire in the d

Responding firefighters use this combination of information to select an action appropriate to the incident at han ·

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

TABLE 9.1 Some Classes of Water-Reactive Substancesa
CLASS OF SUBSTANCE EXAMPLE

CHEMICAL FORMULA HAZARDOUS HYDROLYSIS PRODUCT
Acetyl halides

0
Acet yl bromide // Hydrogen bromide CH3- C

\
Br
0

Acetyl chloride //
Hydrogen chloride CH3-C

\
Cl

Acids Fluorosulfonic acid F- 502-0H Hydrogen fluoride
Nitrosylsulfuric acid

O=N- 0 – 50 2-0-H Nitrogen dioxide
(h lorosilanes Methyldichlorosilane

CH3-Si- Cl2H Hydrogen chloride Methyltrichlorosilane
CH3-Si- Cl3 Hydrogen chloride Trichlorosilane
Cl3Si H Hydrogen chloride

Metallic amides Lithium amide Li NH2 Ammonia
Magnesium diamide Mg(NH2h Ammonia

Metall ic halides Aluminum bromide, AIBr3 Hydrogen bromide anhydrous
Aluminum chloride,
anhydrous AICl3 Hydrogen chloride

Antimony pentafluoride,
anhydrous SbFs Hydrogen fluoride

Metallic hypochlorites Calcium hypochlorite Ca(CI Oh Chlorine, hydrogen chloride
Lithium hypochlorite LiCIO Chlorine, hydrogen chloride

Metallic nitrides Lithium nitride Li 3N Ammon ia
Metallic oxychlorides Chromium oxychloride Cr(OClh Hydrogen chloride
Metallic phosphides Aluminum phosphide AIP Phosphine

Calcium phosphide Ca3P2 Phosphine
Magnesium aluminum Mg3P2 · AIP Phosphine
phosphide
Magnesium phosphide Mg3P2 Phosphine
Potassium phosphide K3P Phosphine
Sodium phosphide Na3P Phosphine
Zinc phosph ide Zn 3P2 Phosph ine

Nonmetallic halides Iodine pentafluoride IFs Hydrogen fluoride
Phosphorus pentachloride PCls Hydrogen chloride
Silicon tetrachloride SiCl4 Hydrogen chloride
Thionyl chloride SOC l2 Hydrogen chloride, sulfur dioxide

Sulfides Ammonium hyarosulfide NH4HS Hydrogen sulfide, ammonia
Ammonium sulfide (N H4)iS Hydrogen sulfide, ammonia –

Others Chlorine dioxide (hydrate)b CI02 Chlorine
Uran ium hexafluoride UF6 Hydrogen fluoride •

Adapted in part from Table 2, Emergency Response Guidebook (Washington, DC. U.S . Department of Transportation, 2012).
bsection 11 .8.

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 311

Lithium metal

TABLE 9.2 Physical Properties of the Alkali Metals

LITHIUM SODIUM POTAss,u~
Melting point 354°F (179°C) 2os°F (9s 0 c) 147°F (54,C)
Boiling point 2437°F (1337°C) 1618°F (881°C) 1425°F (774,
Specific gravity at 68°F (20°C) 0.53 0.97

C)
0.86

Autoignition point 352°F (178°C) 2so°F (121°c)

9.2 ALKALI METALS
We consider the properties of three alkali metals in this section: lithium, sodium
potassium. The properties of these three metals illustrate the uniqueness of their reac~i~nd
Some of their physical properties are noted in Table 9.2. ns.

The alkali metals spontaneously ignite. Furthermore, they displace hydrogen fro
water as the following equations illustrate: tn

2Li(s) + 2H20(/) 2Li0H(aq) + Hz(g)
Lithium Water Lithium hydroxide Hydrogen

2Na(s) + 2H20(l) 2NaOH(aq) + Hz(g)
Sodium Water Sodium hydroxide Hydrogen

2K(s) + 2H20(l) 2KOH(aq) + Hz(g)
Potassium Water Potassium hydroxide Hydrogen

When metallic lithium reacts with water, the hydrogen produced does not immediately
ignite; but when metallic sodium and potassium react with water, the hydrogen bursts
spontaneously into flame as it is produced.

Chemical manufacturers display the GHS flame pictogram on labels affixed to con-
tainers holding the alkali metals.

9 .2-A METALLIC LITHIUM
Lithium is a soft, silvery metal and is the least dense solid element at normal conditions.
Metallic lithium is so light that pieces of it float even in low-density petroleum products
like kerosene and gasoline.

Metallic lithium and lithium compounds are valuable raw materials used to manufac-
ture porcelain, ceramics, castings, batteries, zero-expansion glass, fungicides, bleaching
agents, pharmaceuticals, and greases. In contemporary times, they have become increas-
ingly popular within the chemical industry as raw materials used to synthesize organic
compounds. Metallic lithium itself is a component of a lightweight magnesium alloy.

There are two types of lithium batteries, called primary and secondary lithium batter-
ies. Both types pose the risk of fire. They differ as ‘follows:

Primary lithium-metal batteries. These are disposable, non-rechargeable batteries.
Although they have variable compositions, the most common primary lithium batte~y
uses metallic lithium and manganese dioxide as its electrodes, and lithium perchlorate dis·
solved in propylene carbonate and dimethoxyethane as the electrolyte. Primary lithium·
metal batteries are encountered mainly in the coin or button cells used in watches and
digital cameras. Upon contact with water, they produce hydrogen. .

Secondary lithium-ion batteries. These are rechargeable batteries, also havi~g
variable compositions. A typical type uses a lithium alloy as the positive plate, graphi~e
as the negative plate, and lithium hexafluorophosphate (LiPF6 ) dissolved in an organic

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

C as the electrolyte. Exampl f h . • b d
0Jven es o t e orgaruc solvents are diethyl car onate an s I e carbonate. Secondary lith’ · b . . 11 ethY en _ium-ion attenes are used m laptop computers, ce
hones, powe~ t~ols, _a nd all-el~ctnc automobiles. When damaged, the liquid electrolyte

fn secondary hthmm-ion batteries may ignite.
Both p~imary and secondary lithium batteries may short-circuit and ignite when they

have been u_nproperly packaged ?r damaged. Sufficient heat is generated to cause fire
when they discharge sudden!! durmg short-circuiting. They are also potentially hazardous
because the_ ~Jectrolytes used m them may ignite when exposed to the heat generated during
short-circw~m~. .

When hthmm me~a1. reacts wuh water, the hydrogen is slowly displaced from the
water. The h!drogen dissipates into the surrounding environment without ever achieving
a concentrat_wn equ~l to 0 _r greater than 4% by volume, its lower flammable limit.

During its reaction with water, metallic lithium remains in the solid state of matter.
Although the heat of the reaction initially is absorbed by the metal, it is transmitted to the
surrounding wat~r, the _metal’s temperature remains below the boiling point of water.

When metallic hthmm is left exposed to the air at room conditions, it does not spon-
taneously ignite. Although the metal oxidizes in the air it does so very slowly. Even mol-
ten lithium oxidizes so slowly that it can be poured from a container in the open air
without losing its bright luster.

In an atmosphere of absolutely dry air, lithium metal does not spontaneously burn.
When exposed to an ignition source, however, the metal burns in the air with a character-
istic crimson color, forrning a mixture of lithium oxide and lithium nitride.

4Li(s) + Oz(g) 2Li20(s)
Lithium Oxygen Lithium oxide

6Li(s) + Nz(g) 2Li3N(s)
Lithium Nitrogen Lithium nitli de

9.2-B METALLIC SODIUM
Like metallic lithium, sodium also is a soft, silvery bright metal. It is the most commonly
encountered alkali metal and the only one produced in bulk. Sodium metal generally is
available for commercial use in the form of solid bricks.

The majority of the metallic sodium produced in the United States formerly was used
as a raw material for the manufacture of the vehicular fuel additives tetraethyllead and
tetramethyllead. This use of metallic sodium was sharply curtailed in 1975, when EPA
banned the use of leaded gasoline in vehicular fuels. Today, metallic sodium is used pri-
marily as a raw material for the production of highly reactive sodium compounds such as
sodium peroxide and sodium hydride. In addition, metallic sodium is used as a catalyst
during the production of certain types of synthetic rubber.

Metallic sodium sometimes is encountered commercially in alloys such as sodium/
potassium alloys, sodium/lead alloys, and sodium amalgams. An alloy is a solid mixture
of two or more elements, none of which can be separated by mechanical means. An
amalgam is a special alloy in which one of these elements is elemental mercury. When a
sodium alloy or amalgam is used instead of sodium alone, sodium reacts less vigorously.
Consequently, chemical manufacturers often use sodium alloys and amalgams when the
rate of a reaction requires careful control; notwithstanding this fact, the use of all amal-
gams has lost its popularity owing to the toxicity of mercury.

Metallic sodium reacts rapidly with water. In fact, the reaction occurs so rapidly that
the hydrogen produced is unable to dissipate before it ignites. Instead, it concentrates in
the immediate vicinity of the metal, where, induced by the heat of reaction, it self-ignites
and spontaneously burns. The metallic sodium absorbs the heat .of reaction and melts,
thereby exposing an underlying surface of the solid metal for further reaction.

Sodium metal

A solid mixture
of two or more
mechanically
inseparable elements

amalgam An alloy of
mercury with one or
more elements

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 313

Potassium metal

metallic superoxide
(metallic hyperoxide)

An inorganic
compound composed
of metallic and
superoxide ions

Unlike lithium, metallic sodium does not react with atmospheric nitrog
sod~um burns in an atmosphere of oxygen, producing a mixture of sodiu~: ~eta.Ilic
sodmm peroxide. Xide and

4Na(s) + 02(g) –+ 2Na20(s)
Sodium Oxygen Sodium oxide

2Na(s) + 02(g) –+ Na202(s)
Sodium Oxygen Sodi um peroxide

Because sodium peroxide is a powerful oxidizer (Section 11.16-A), it itself is ah
material. azardaus

Although bulk sodium is not pyrophoric, nonbulk pieces of metallic sodiu .
spontaneously at room temperature with a characteristic yellow flame . In absol 111 :gnite
air, however, this oxidation does not occur at an appreciable rate, which suggest~~~ Y dry
oxidation of metallic sodium in air is triggered by the reaction of metallic sod· at the

h . . 1 f . . . d’ tum and atmosp enc water vapor. To reduce its potentia or Igmtton, so mm generally is st
under kerosene. 0red

9.2-C METALLIC POTASSIUM
Potassium is a soft, silvery metal. Although it formerly was used with sodium as a he
exchanger fluid in nuclear reactors, metallic potassium now has so few commercial u at.
h . . t at It IS rarely encountered.

The combustion of potassium metal in air is associated with the production of a cha _
acteristic purple flame. The combustion product is primarily potassium oxide. r

4K(s) + 02(g) –+ 2K20(s)
Potassium Oxygen Potassium oxide

When potassium burns in an atmosphere of pure oxygen, however, a mixture of potassium
oxide, potassium peroxide, and potassium superoxide is produced.

2K(s) + 02(g) –+ K202(s)
Potassium Oxygen Potassium peroxide

K(s) + 02(g) –+ K02(s)
Potassium Oxygen Potassium superoxide

A superoxide, more properly called a hyperoxide, is a compound containing the superoxide
ion, whose chemical formula is 0 2. Metallic superoxides (metallic hyperoxides} are
extraordinarily reactive oxidizing agents (Section 11.16-B).

Metallic potassium reacts with water even more rapidly than does sodium. The vigorous
nature of this reaction most likely is due to the presence of minute amounts of potassium
superoxide produced when potassium oxidizes. The hydrogen produced by the reaction of
potassium and water initially concentrates around the metal, where it self-ignites; then,_ the
heat of reaction triggers the burning of the potassium metal. The reaction between potassium
superoxide and atmospheric moisture occurs with such ease that it has been employed com·
mercially as a means of supplying oxygen in self-contained breathing apparatus.

9 .2-D TRANSPORTING ALKALI METALS AND
PRIMARY LITHIUM BATTERIES

When shippers offer an alkali metal or its alloys, amalgams, or dispersions for transpo~a-
tion, DOT requires them to identify the appropriate material on the accompanying shiP~0f
paper. The shipping descriptions of some representative examples are listed in Table . · ·
DOT also requires shippers and carriers to comply with all applicable labeling, rnarklllg,
and placarding requirements.

314 Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

!(ALI METAL S,
AL ERSIONS, ALLOYS, OR PRODUCTS SHIPPING DESCRIPTION 01SP

OR ITS AMALGAM

I’ metal alloys (liquid)
Alka 1 UN1421, Alkali metal alloy, liquid, n.o.s., 4.3, PG I

(Dangerous When Wet)

Alkali metal dispersions UN1391, Alkali metal dispersion, flammable, 4.3, PG I
(Dangerous When Wet)

Alkaline earth metal alloys UN1393, Alkaline earth metal alloy, n.o.s., 4.3, PG II

Lithium UN1415, Lithium, 4.3, PG I (Dangerous When Wet)

Primary lithium metal battery UN3090, Lithium battery, 9, PG II (Dangerous When Wet)

Primary lithium metal batteries, contained UN3091, Lithium battery, contained in equipment, 9,
in equipment PG II (Dangerous When Wet)

Primary lithium metal batteries, packed UN3091, Lithium battery, packed with equipment, 9,
with equipment PG II (Dangerous When Wet)
–
potassium UN2257, Potassium, 4.3, PG I (Dangerous When Wet)
–
Sodium UN1428, Sodium, 4.3, PG I (Dangerous Whe nWet

The transportation of primary lithium batteries is subject to additional regulations
published at 49 C.F.R. §173.185. DOT requires manufacturers, shippers, and carriers to
implement certain safety precautions when offering lithium-metal batteries for transpor-
tation. For example, shippers must package individual lithium-metal batteries in an inner
packaging, separated by a divider and surrounded by noncombustible, nonconductive
cushioning that prevents contact of the battery terminals with other batteries, metal
objects, or conductive surfaces. Strong outer packaging or containment that complies
with Packing-Group-II performance standards also is required.

When transporting primary lithium batteries domestically, DOT requires shippers to
include the following statement on the shipping paper:

This shipment contains primary lithium batteries. Do not damage or mishandle
the packages. If the package is damaged, flammability hazard may exist; batteries
must be quarantined, inspected, and repacked.

When shippers intend to transport lithium-metal batteries by aircraft, DOT also
requires them at 49 C.F.R. §172.102.188 to affix the lithium-battery-handling label
shown in Figure 9.2 on two opposing sides or ends {other than the bottom) of the packag-
ing, and to provide either of the following markings on its surface:

PRIMARY LITHIUM BATTERIES –
FORBIDDEN FOR TRANSPORT

ABOARD PASSENGER AIRCRAFT

LITHIUM METAL BATTERIES –
FORBIDDEN FOR TRANSPORT

ABOARD PASSENGER AIRCRAFT

When shippers intend to transport lithium-metal batteries by cargo aircraft, DOT also
requires the CLASS 9 and CARGO AIRCRAFT ONLY labels shown in Figures 6.5 and 6.6,

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 315

TABLE 9.3 Shipping Descriptions of Some Representative Alkali
Metals, Their Amalgams, Dispersions, Alloys, and Products

ALKALI METAL OR ITS AMALGAMS,
DISPERSIONS, ALLOYS, OR PRODUCTS SHIPPING DESCRIPTION
Alkali metal alloys (liquid) UN1421, Alkali metal alloy, liquid, n.o.s., 4.3, PG I

(Dangerous When Wet)
Alkali metal dispersions UN1391, Alkali metal dispersion, flammable, 4.3, PG I

(Dangerous When Wet) –
Alkaline earth metal alloys UN1393, Alkaline earth metal alloy, n.o.s., 4.3, PG II
Lithium UN1415, Lithium, 4.3, PG I (Dangerous When Wet)
Primary lithium metal battery UN3090, Lithium battery, 9, PG II (Dangerous When Wet)
Primary lithium metal batteries, contained UN3091, Lithium battery, contained in equipment, 9,
in equipment PG II (Dangerous When Wet)
Primary lithium metal batteries, packed UN3091, Lithium battery, packed with equipment, 9,
with equipment PG II (Dangerous When Wet)

Potassium UN2257, Potassium, 4.3, PG I (Dangerous When Wet)

Sod ium UN1428 S , odium, 4.3, PG I (Dangerous When Wet)

The transportation of primary lithium batteries is subject to additional regulations
published at 49 C.F.R. §173.185. DOT requires manufacturers, shippers, and carriers to
implement certain safety precautions when offering lithium-metal batteries for transpor-
tation. For example, shippers must package individual lithium-metal batteries in an inner
packaging, separated by a divider and surrounded by noncombustible, nonconductive
cushioning that prevents contact of the battery terminals with other batteries, metal
objects, or conductive surfaces. Strong outer packaging or containment that complies
with Packing-Group-II performance standards also is required.
When transporting primary lithium batteries domestically, DOT requires shippers to
include the following statement on the shipping paper:
This shipment contains primary lithium batteries. Do not damage or mishandle
the packages. If the package is damaged, flammability hazard may exist; batteries
must be quarantined, inspected, and repacked.

When shippers intend to transport lithium-metal batteries by aircraft, DOT also
requires them at 49 C.F.R. §172.102.188 to affix the lithium-battery-handling label
shown in Figure 9.2 on two opposing sides or ends (other than the bottom) of the packag-
ing, and to provide either of the following markings on its surface:

PRIMARY LITHIUM BATTERIES –
FORBIDDEN FOR TRANSPORT
ABOARD PASSENGER AIRCRAFT
LITHIUM METAL BATTERIES –
FORBIDDEN FOR TRANSPORT
ABOARD PASSENGER AIRCRAFT
When shippers intend to transport lithium-metal batteries by cargo aircraft, DOT also
requires the CLASS 9 and CARGO AIRCRAFT ONLY labels shown in Figures 6.5 and 6.6,
Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 315

FIGURE 9.2 When pack-
ages of lithium-metal bat-
teries are transported by
cargo aircraft, DOT
requires shippers to affix
this lithium-battery han-
dling label on opposing
sides of each package
adjacent to a CLASS 9
and a CARGO AIRCRAFT
ONLY label. The printing
on the lithium-battery-
handling label is black
with a red-hatching bor-
der on a contrasting
background.

combustible
Any metal

whose distinct particles
or pieces, regardless of
size or shape, can read- ·
ily ignite to produce an
NFPA class D fire

~,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,~
s s

CAUTION!
Lithium Metal Battery

II A ! 111 ,=
DO NOT LOAD OR TRANSPORT

PACKAGE IF DAMAGED
For Emergency information, call CHEMTREC:

S 1-800-424-9300 – North America S
1-703-527-3887 – International

For product information, call 315-332-7100

~””””””””””””””””””””'”‘

respectively, to be affixed adjacent to each other on two opposing sides or ends (other th
the bottom) of the packaging. DOT also regulates the nature of the packaging to reduce t~n
likelihood of short circuiting and damage to battery terminals. e

The Federal Aviation Administration does not permit large palletized shipments of
primary lithium batteries on cargo or passenger aircraft. Furthermore, although DOT
permits the transportation of primary lithium batteries contained in electronic equipment
it does not permit air transport of loose lithium batteries in checked baggage. ‘

9.3 COMBUSTIBLE METALS
Magnesium, titanium, zirconium, aluminum, and zinc possess a common hazardous fea-
ture. Although bulk pieces of these metals typically are difficult to ignite, their finely
divided forms may self-ignite in air without exposure to an ignition source. They are
examples of combustible metals, some of which are also pyrophoric at elevated tempera-
tures. These metals represent the fuels of class D fires. Some of their relevant physical
properties are provided in Table 9.4.

Chemical manufacturers display the GHS flame pictogram on labels affixed to con-
tainers holding hazardous forms of the combustible metals.

The finely divided forms of some combustible metals are regarded as water- and air-
reactive substances to varying degrees. They include dusts, powders, chips, turnings,
flakes, punchings, borings, ribbons, and shavings. These forms are commonly produced
during metal-forging and metal-machining operations. Often, the heat retained from these
processes is sufficient to cause the metals to spontaneously ignite. The finely divided forms
of metals generated during machining, grinding, boring, and other fabrication processes
are also likely to be coated with the cutting oils used as lubricants, which can ignite as the
primary fuel. .

The finely divided forms of combustible metals react with water to produce hy~o-
gen. The spontaneous ignition of the hydrogen kindles the burning of the underlying
metal. The rate of hydrogen production is affected by a number of factors including the
particle size, distribution and dispersion, purity, and ignition temperature of the metal, as
well as the moisture content of the surrounding atmosphere. Some relevant physical prop·
erties of these metals are provided in Table 9.4.

316 Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

TABLE 9.4 Physical Properties of Several Combustible Metals

MAGNESIUM ZIRCONIUM

Melting point , 200°F (649°C) 3326°F (1830°()

soiling point 2012°F (11 oo•q 7911 °F (4377°C)
‘fc gravity at 68°F (20°() 1.74 6.49 speCI I

,Autoignition point 883°F (472. 18°c) 662°F (3S0°C)
(powder) (powder)
9S0°F (s10°c)
(ribbons and shavings)
1202°F (6so 0 c)
(massive chunks)

ALUMINUM ZINC

Melting point 1220°F (660°c) 786°F (419°C)

soiling point 4221 °F (2327°C) 1665°F (907°C)

Specific gravity at 68°F (20°() 2.70 7.14

Autoignition point 1400°F (760°() 860°F (460°c)
( owder owder p (p

9.3-A METALLIC MAGNESIUM
As previously noted in Table 4.1, magnesium occurs to the extent of 1.9% by mass on Earth’s
surface, where it typically is found in such ores as magnesite, dolomite, soapstone, and
brucite. Magnesium is also found extensively in underground brines, mainly as magnesium
chloride. It is also present in seawater as magnesium chloride and magnesium sulfate.

Magnesium metal is produced mainly for commercial use by the electrolysis of a mol-
ten mixture of anhydrous magnesium chloride and potassium chloride.

MgClz(/) Mg(/) + Clz(g)
Magnesium chloride Magnes ium Chl01ine

The potassium chloride increases the conductivity of the salt mixture and reduces its melt-
ing point. At the temperature of the electrolytic cell, molten magnesium floats on the salt
mixture and is periodically removed through a trough and poured into molds.

Magnesium is an exceptionally lightweight metal. It therefore is often employed in
the construction of aircraft, racing cars, transportable machinery, engine parts, automo-
bile frames and bumpers, wheel rims, and other items for which the mass of the object is
pertinent. Because of its popularity, magnesium is commercially available in a variety of
sizes ranging from a dust or powder to massive ingots.

As illustrated by the following examples, magnesium is a very reactive metal:

1 Although it reacts slowly with cold water, magnesium reacts rapidly with warm and
hot water, producing hydrogen.

Mg(s) + 2H2O(l) Mg(OH)z(s) + Hz(g)
Magnesiu m Water Magnesium hydroxide Hydrogen

1 Metallic magnesium is also a strong reducing agent. This property is put to use in the
metal manufacturing industry, where molten metallic magnesium is used to reduce
the metals in certain ores such as those containing titanium and zirconium com-
pounds. Magnesium powder is also used as a reducing agent in many fireworks in
which its reactions contribute to the production of brilliant displays of light. ‘

TITANIUM
3034°F (1668°()

5948°F (3260°()

4.51
482°F (2so 0 0
(3. 175-mm-thick plate);
>2192°F (>1200°C)
(6.35-mm-diameter rod)

Magnesium metal
turnings

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 317

metal fume fever The
occupational disease
associated with inhal-
ing metal fumes and
dusts, especially of
magnesium and zinc

Titanium metal
powder

1 The most well-known chemical property of magnesium metal is its comb
; emental magnesium burns, approximately 75% combines with atmosphe ~stibility A
orm magnesium oxide . rte oicyge~ ·11

tG
2Mg (s) + 0 2(g) 2Mg0(s)

Magnesium Oxyge n Magnesium oxide

The remaining 25% combines with atmospheric nitrogen to form magnesium ..
llttr1de

3Mg(s) + N2(g) Mg3N 2(s) .
Magnesium Nitrogen Magnesiu m nit1i de

~agnesium ribbon once was used in one-time-use photo flashbulbs to illum·
with a brilliant flash of light. Inate scenes

The burning of bulk pieces of magnesium is hazardous. When raised to ate
of 1200°F (649°_C), massive_ingots, casting~, and ot~e_r bulk ~on!1s of metallic rn~P~ra~ure
me~t and burn v~go~ously with the producu_o~ ?f bnll1~nt, blmdmg white flam.es. t est~lll
as it flows, the hqmd metal drops from its m1t1al locat10n to lower levels where . ~ntng

b ‘b ‘ 1t 1g · com ust1 le materials encountered in its pathway. ll!tes
. ln~ividuals exposed to magnesium fumes are at risk of contracting metal furne f

This disease is characterized by a rise in body temperature, cough, sore throat, chest ~Ver.
ness, headache, fever, metallic taste, nausea, vomiting, and blurred vision. tight-

9 .3-8 METALLIC TITANIUM
As noted in Table 4 .1, titanium occurs on Earth’s surface to the extent of 0.58% by mas
The element occurs primarily as titanium(IV) oxide . One such ore, rutile, is abundant t’
beach sands in Australia, South Africa, and Sri Lanka. n

The titanium manufacturing process consists of the following two steps:

First, rutile or a similar ore is reacted with chlorine and carbon at approximately
1112 °F ( 600°C) to produce titanium(IV) chloride.

Ti02(s) + 2C(s) + 2Cl2(g) TiCl4(g) + 2CO (g)
Titanium(IV) oxide Carbon Chlorine Titan ium(IV) chloride Carbon monoxide

Then, titanium(IV) chloride is reacted with molten magnesium within a steel vessel under
an atmosphere of an inert gas like helium or argon at approximately 1472°F (800°C).

TiCl4(g) + 2Mg (/) Ti (s) + 2MgC12(s)
Titanium(IV) chloride Magnesium Titanium Magnesium chl oride

The magnesium chloride formed as a by-product is leached from the reaction mix·
ture, leaving the basic form of the metal known as titanium sponge, so called because
its physical appearance resembles the shape of a sponge. ·

These production steps are costly, which currently hinders the widespread use of titanium,
Although it is 45% lighter in mass than steel, metallic titanium is just as strong as

steel. Because titanium possesses this combination of lightness and strength, it often 1~
alloyed with aluminum and vanadium, which then is used to manufacture air~~aft an r
automotive p_arts,_ jet eng~nes, and_ miss~les. In mo~ern-~ay commerc~al and milit::i/:s
aircraft, titaruum 1s replacmg alumm1,1m m blades, discs, rmgs, and engme cases, as
bulkheads, tail sections, landing gear, wing supports, and fasteners. . and

In the automotive industry, titanium metal now is used in several consumer car·ngs
motorcycle applications. It is used primarily for exhaust systems, suspension spri ‘
engine valves, connecting rods, and turbocharger compressor wheels.

318 Chapter g Chemistry of Some Water- and Air-Reactive Substances

atlic titanium is also found in everyday items such as jewelry, skis, and golf
_M;:nr. Titanium prostheses often are selected by orthopedic surgeons for hip and

eqU1P lacements .
kne~;:nium m_etal h~s a great a_ffinity for oxygen. Once exposed to air, a thin layer of

. n(IV) oxide quickly deposits on the surface of the metal and protects the underly-
tifl1111~al from further chemical attack. Then, the metal is highly resistant to corrosion by
ing uie ‘ds chlorine, oxidizing agents, and seawater.

osr ac1 ‘ f . . h . . . 111 The resistance o tlta~mm to c em1cal attack has been put to good use m various
•ocluding the followmg:

1113)’5, I

1
Because it is lightweight and resistant to corrosion by seawater, metall_ic tita~ium is
used in the stru~ture of underwater machinery. Most likely, its corros10n resistance
was an influencmg factor that prompted Russia in 2007 to mount a flag made from
riranium on the ocean floor at the North Pole from a deep-submergence vehicle.

1 Because metallic titanium is resistant to corrosion by seawater, the U.S. Office of
Naval Research ordered its first ship hull constructed entirely from it in 2012.

1 Because it is resistant to corrosion by most acids and chlorine, metallic titanium is
also used in the construction of vessels in which these raw materials will be stored,
transported, or reacted. One notable exception to this general observation, however,
is hydrofluoric acid, which reacts with metallic titanium.

Although the bulk forms of titanium are not considered hazardous, Table 9.4
shows that titanium has the lowest auto-ignition point of the combustible metals.
Finely divided titanium poses a dangerous risk of fire and explosion. It is generated
when fabrication operations are conducted on titanium and its pieces are cut, formed,
and welded.

When metallic titanium burns in air, a mixture of titanium(IV) oxide and titanium(III)
nitride is produced.

Titanium Oxygen Titanium(IV) oxide

2Ti(s) + N2(g) – 2TiN(s) .
Titanium Nitrogen Titanium(lll) nitride

The reactions may be initiated by the combustion of the hydrogen produced when the
finely divided metal reacts with atmospheric moisture.

Ti(s) + 2H20(g) – Ti02(s) + 2H2(g)
Titanium Water Titanium(lV) ox ide Hydrogen

9.3-C METALLIC ZIRCONIUM
Metallic zirconium is produced primarily from zirconia, a naturally occurring ore con-
taining zirconium(IV) oxide (ZrO 2 ), by the method just described for production of tita-
nium. Today, the metal is used almost exclusively in the nuclear and steel industries. In the
nuclear industry, tubes made of a zirconium alloy are used to hold the uranium(IV) oxide
pellets needed as fuel for use in reactor cores (Section 16.9-C), and in the steel industry,
zirconium is used to remove oxygen from molten steel. Zirconium dust formerly was used
as the active component of specialized camera photoflash bulbs, and it has also been used
militarily as an incendiary agent. · –

Zirconium dust constitutes a risk of fire and explosion. When it is transferred from
one container to another, the dust particles absorb the heat generated by friction as the
Particles move against one another. When these particles are hot, as when they are first
Produced, the temperature of the dust can exceed its autoignition point, whereupon it
spontaneously ignites.

Zirconium metal
powder/dust

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 319

Aluminum metal
powder/dust

malleable The prop-
erty or capability of
being rolled or ham-
mered into shapes

The ease of ignition of zirconium dust is associated with its former use as~
diary agent in a shotgun round known as Dragon’s Breath , The round, when inincen.
into the magazine of a shotgun, burst into flame when the gun ~as fired and shors?ted
the gun’s barrel like a flamethrower. Zirconium dust, however, is extremely exp r.oni

. . ·1· f D ens1v Despite its fearsomeness in application, the routme mi itary use O ragon’s Breath~-
cost-prohibitive. . . . is

When zirconium dust burns in air, the resultmg fire provides an exceedingly b il]j·
d . f . f . r ant white flame. The combustion results in the pro uction o a mixture o zirconium OJ( ,

d · · · ‘d 1de an zircoruum rutn e.
Zr(s) + Oz(g) Zr02(s)

Zirconium Oxygen Zirconium oxide

2Zr(s) + N z(g) 2ZrN (s)
Zirconium Nitrogen Zirconium nitride

The reactions may be initiated by the combustion of hydrogen, produced when the dust
reacts with hot atmospheric moisture.

Zr(s) + 2H20(g) Zr02(s) + 2Hz(g)
Zirconium Water Zirconium oxide Hydrogen

Water does not react with the zirconium alloy used in nuclear reactors; in fact, under
normal operating conditions, it cools their fuel assemblies. When zirconium or its alloy is
red-hot, however, the metal decomposes water to form hydrogen. When hydrogen is pro-
duced at malfunctioning nuclear reactor sites, it must be vented to the outside environ-
ment to prevent the confinement vessel from exploding.

9.3-D METALLIC ALUMINUM
Table 4.1 lists aluminum as the most abundant metal on Earth’s surface, 7.5% by mass.
As the element, aluminum is too reactive to be found in an uncombined form in nature.
Instead, it is found in minerals like cryolite and in such materials as clay and feldspar, in
which it is combined with silicon and oxygen.

Aluminum metal is produced by the electrolysis of aluminum oxide dissolved in fused
cryolite, which serves as the electrolyte.

2Al203(s) 4Al(l) + 30z(g)
Alu mi num oxide Aluminum Oxygen

The aluminum metal is denser than molten cryolite; therefore, it collects at the bottom of
the electrolytic cell, from which it is tapped and cast into ingots.

Aluminum is an example of a malleable metal; that is, it can be rolled or ham·
mered into a relatively thin sheet or foil. Aluminum foil is a popular kitchen item.
Firefighters encounter aluminum foil bonded to fabric in aluminized protective suits
that are worn when they must approach fires that release exceptionally high levels of
radiant heat.

Because it is lightweight and durable, aluminum sheeting is used to produce a
wide variety of commercial products including the common soda can. In building
construction, aluminum sheeting is used as siding, eaves, screens, and window and
door frames. During building fires, these aluminum components can melt and col·
lapse, because the temperature attained often exceeds the melting point of aluminum,
1220°F (660°C).

The principal material employed as the metal skin of most standard aircraft is an alu·
min_um_ or aluminum alloy sheet!ng. The metal cannot be used as the outer skin of supe~
some aircraft, however, because 1t becomes too hot and softens from the friction generate
by the fast movement through the air.

320 Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

Magnesium ribbon

T
10 in.

Pan of dry sand

GURE 9,3 In this laboratory demonstration, a mixture of powdered aluminum and iron(III) oxide is inserted
~~to a cone over a pan of dry sand (wh~ch protects the tabletop from possible damage). A magnesium ribb~n is
. rted into the thermite mixture and ignited. The heat of combustion initiates the reaction between aluminum
;; iron(III) oxide. Molten iron spits from the reaction mixture and drips into the sand.

Aluminum is also a ductile substance; that is, it can be drawn into wires. Although
aluminum wire is twice as effective as copper wire for conducting electricity, the use
of aluminum electrical wiring is undesirable. This is because the heavy deposit of
aluminum oxide produced on the surface of aluminum wiring restricts the flow of
dectrical current and causes the metal to become overheated. This situation constitutes
a fire hazard.

The deposition of aluminum oxide on the surface of aluminum wiring is associated
with the extraordinary affinity that aluminum and oxygen have for each other. Aluminum
exposed to air is covered with a thin, tenacious coating of aluminum oxide that gives the
metal a dull, white luster. Although this oxide coating protects the underlying metal from
further oxidation, the coating does not protect the aluminum from other forms of chemi-
cal attack. Seawater, for instance, corrodes metallic aluminum.

This chemical affinity of metallic aluminum for oxygen is evident from the chemical
reaction noted in Figure 9.3 involving powdered aluminum and iron(III) oxide. The mix-
ture of 27% powdered aluminum and 73% iron(III) oxide is commonly called thermite.
When the mixture is activated by a magnesium fuse, a reaction producing molten iron and
aluminum oxide occurs.

Aluminum Ferric oxide Iron Aluminum oxide

This phenomenon is called the thermite reaction. It releases such considerable heat that
temperatures of approximately 3990°F (2199°C) result. Because this temperature is above
the melting point of iron [2800°F (1538°C)], it is produced by this chemical reaction as a
molten, white-hot liquid. The thermite reaction cannot be stopped with water.

In the days of the old West, the thermite reaction was used to weld rails together
during the construction of railroads. During World War II, thermite was used exten-
sively as the incendiary agent in bombs, especially against the British during the
London Blitz. In contemporary warfare, however, the use of thermite in incendiary
~eapons is essentially banned by Protocol III of the Convention on Certain Conven-
tional Weapons (Section 7.3 ). Protocol III limits the use of all incendiary weapons
against civilian targets.

ductile The property
of metals associated
with their capability of
being stretched into
wires

thermite The mixture
of 27% powdered
aluminum and 73%
iron(lll) oxide

thermite reaction The
chemical reaction used
in some welding opera-
tions and incendiary
weapons during which
elemental iron is pro-
duced by the reduction
of iron(III) oxide with
elemental aluminum

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 321

CHAPTER

Courtesy of Bulk Transportation, Inc., Walnut, California.

i3flh;iMfA
acid, p. 27

2

acidic. p. 27

4

8
Chemistry of Some
Corrosive Materials

oxidizing acid, p. 274
pH, p. 274
pickling, p. 278

–
acidic anhydride (nonmetallic
oxide), p. 27

7

concentrate

d

acid, p. 274
corrosive material, p. 271
corrosive substance, p. 271
diluted acid, p. 274
hydronium ion, p. 272
hypocalcemia, p. 292
mineral acid, p. 27

3

nonoxidizing acid, p. 274

RCRA corrosivity characteristic, p. 30

0

salt, p . 276

alkaline, p . 274
anhydride, p. 277
aqua regia, p. 285
base,p. 272
basic (caustic), p. 274
basic anhydride (metallic oxide), p. 277

oleum (fuming sulfuric acid), p. 282
organic acid (carboxylic acid), p. 274

slaking, p. 29

9

strong acid, p. 273
strong base, p. 273
weak acid, p. 273
weak base, p. 273

i•1=!ii3ir,tA
Associate the physical and health hazards of the corrosive materials noted in this
chapter with the information provided by their hazard diamonds and GHS
pictograms.
Identify the primary industries that use the corrosive materials noted in this chapter.
Identify the concentrated acids that vaporize at room temperature and cause ill
effects when inhaled.
Identify the labels, markings, and placards that DOT requires on packaging of cor-
rosive materials and the transport vehicles used for their shipment.
Identify the response actions to be executed when corrosive materials are released
from their packaging into the environment.

270

The most common examples of · · · ll ‘d d b corrosive materials are substances known chem1-ca as ac1 s an ases T . . . • Y . d · hey are compounds capable of causmg 1rritat1on, burns, or more serious amage to tissu d d’ h · · ·
h b

. e, epen mg on t e1r strength. Their umque prop-
·es and t e manner y which acids d b d • · · ertl an ases corro e matter are the prmc1pal subiects

of this chapter.

s.1 THE NATURE OF CORROSIVITV
Corrosivity is a chemical property exhibited by certain substances. In everyday practice,
we sa~ that these substances “ea~ into” and destroy the quality of metals, minerals, and
body tissues. Government regulat10ns, however, provide more specificity as the following
definitions demonstrate: ‘

CPSC defines _a corrosive substance as any consumer product that destroys liv-
ing tissue such as _skm or eyes by chemical action . At 16 C.F.R. §1500.41, a product is
considered corrosive to the skin if, when tested on the intact skin of the albino rabbit
the structure of the tissue at the site of contact is destroyed or changed irreversibly i~
24 hours or less.

DOT defines a corrosive material as a liquid or solid that causes full-thickness
destruction of human skin at the site of contact within a specified period, or a liquid that
chemically reacts with steel or aluminum surfaces at a rate exceeding 0.25 inches/year
(6.25 mm/y) at a test temperature of 130°F (54°C) when measured in accordance with
prescribed testing procedures.

During emergency response actions, corrosive materials often are encountered in non-
bulk containers like lined steel drums (1A1 or 1A2), plastic drums (1H1 or 1H2), and
plastic carboys (3H1 or 3H2). As a minimum, OSHA requires manufacturers, distribu-
tors, and importers of chemical products to post the corrosion-symbol pictogram on the
labels of corrosive materials, along with an appropriate hazard signal word and hazard
and precautionary statements.

Corrosive materials are transported in bulk in rail tankcars or cargo tanks. Both the
DOT-111 rail tankcar and MC-312 cargo tank are low-pressure [<75 psi (517 kPa)] transport vessels manufactured from steel and generally lined with rubber. Their design and construction features are published at 49 C.F.R. § § 173.242 and 178.343, respec- tively. To provide an element of safety, the MC-312 cargo tank is equipped with stiffening rings and rollover protection. . .

When carriers transport 1001 pounds (454 kg) or more of a corrosive material, DOT
requires them to display CORROSIVE placards on the bulk packaging used for shipment.
When more than one corrosive material is transported in a compartmented tankcar or
c~rgo tank, DOT requires carriers to placard each compartment separately as shown in
Figure 8.1.
to :When carriers transport corrosive materials by highway or rail, DOT requires them

display the relevant identification number on orange panels or across the center area
ofhthe CORROSIVE placards or white square-on-point diamonds. For example,
:/n sod~um hydroxide (Section 8.14), a corrosive material, ~s tran~po_rted ?~ h1?h-
n Y or rail, carriers may use any of the following means to display its identif1cat10n
Ulllber 1824:

corrosive substance
For purposes of

CPSC regulations, any
substance that causes
the destruction of
living tissue by
chemical action

corrosive material For
purposes of DOT
regulations, a liquid or
solid that causes full-
thickness destruction of
human skin at the site
of contact within a
specified period; or a
liquid that chemically
reacts with steel or
aluminum surfaces at
a rate exceeding
0.25 inches/year
(6.25 mm/y) at a test
temperature of 130°F
(54°C) when measured
in accordance with
prescribed testing
procedures

L

Chapter 8 Chemistry of Some Corrosive Materials

271

acid A compound that
forms hydrated hydro-
gen ions, W(aq), when
dissolved in water

hydronium ion The
simplest hydrated
hydrogen ion,denoted
as H(H 2O}’, or H3o•

A hydroxide of
the alkali and alkaline
earth metals and certain
other substances whose
aqueous solutions have
a pH greater than 7

. FIGURE 8 .1 DOT requires the front and rear ends
of a compartmented cargo tank to be placarded in
same sequence as the compartments are being
transported . This three-compartment cargo tank is
placarded to transport caustic soda solution, for-
mic acid, and an “other regulated liquid sub-
stance .” The latter is a class 9 hazardous material,
whereas caustic soda solution and formic acid are
class 8 corrosive materials. To comply with DOT
marking requirements, the carrier has posted
identification numbers across the center of each
placard . (Courtesy of Bulk Transportation, Inc.,
Walnut, California.)

8.2 THE NATURE OF ACIDS AND BASES
Several theories have been proposed to account for the properties of acids and bases, but
for simplicity’s sake, we use only one of them in this text. In 1887, Swedish chemist
Svante Arrhenius first advocated a theory that has been modernized here to reflect current
scientific knowledge. Arrhenius proposed that an acid is any substance that generates
hydrogen ions (H•) when dissolved in water. Hydrogen ions are hydrogen atoms that have
been stripped of their electrons. A single hydrogen ion is the same as the nucleus of a
hydrogen atom, or a single proton.

Today, chemists know that free hydrogen ions cannot exist alone in aqueous solution due
to their high charge density. Instead, they rapidly become “solvated”; that is, they bond loosely
to water molecules. These solvated hydrogen ions are very complex in the manner in which
they interact with water. The simplest ion is H(H20)+, or H3 0•; it is called the hydronium ion.
We collectively represent here all solvated hydrogen ions by the notation H•(aq).

For instance, when hydrogen chloride dissolves in water, solvated hydrogen ions and
chloride ions are generated.

HCl(aq) H +(aq) + c 1-(aq)
Hydrogen chlori de Hy drogen ion Chloride ion

This solution of hydrogen chloride in water is called hydrochloric acid. Its chemical formula
is HCl(aq ).

Arrhenius further proposed that a base is a substance that produces hydroxide io~s
(OH-) when it is dissolved in water. For example, when sodium hydroxide dissolves ill
water, solvated sodium and hydroxide ions are generated. We represent them as Na• (aq )
and OH-(aq ), respectively.

NaOH(aq) Na +(aq) + OH-(aq)
Sodiu m hydrox ide Sodium ion Hyd rox ide ion

The solution of sodium hydroxide in water is represented as N aOH(aq ).

272 Chapter 8 Chemistry of Some Corrosive Materials

s.2-A STRONG AND WEAK ACIDS AND BASES

I

is the ability of acids and bases to form ions in water that gives rise to their corrosive
nrarure. The relative strength of an aci~ or base refers to the tendency of an individ~al
substance to form hydrated hydrogen ions and hydroxide ions, respectively, when dis-

.
so Acids and bases that yield a relatively high concentration in water of hydrated hydro-
gen and hydroxide _ions_ a~e called strong acids and strong bases, respectively. ~or
jnsrance, hydrochl~nc_ aci~ is an example of a strong acid, because the hydrogen chlonde
fmost completely 10mzes m water. Likewise, sodium hydroxide is an example of a strong

~ase, because it almost completely ionizes in water.
In contrast, some substances essentially retain their unit formulas when they are dis-

solved in water. Such substances yield relatively low concentrations of hydrogen or
hydroxide ions and ar~ called we~k a~ids and weak bases, respectively. Acetic acid i~ a_n
example of a weak acid, because It pnmarily exists as molecules of acetic acid when 1t 1s
dissolved in water, although some hydrogen and acetate ions are also produced. Ammo-
nium hydroxide is an example of a weak base. When ammonia is dissolved in water, it
continues to exist primarily as molecular ammonia and does not appreciably from ammo-
nium and hydroxide ions.

Each acid in the group listed in Table 8.1 is ranked as a strong or a weak acid.
Phosphoric acid is regarded as a moderately strong acid, whereas the acids above and
below phosphoric acid in this listing are considered strong acids and weak acids,
respectively.

8.2-B MINERAL ACIDS AND ORGANIC ACIDS
Acids may be classified as either mineral acids or organic acids. Mineral acids consist of
molecules having atoms of hydrogen; an identifying nonmetal like chlorine, sulfur, or
phosphorus; and sometimes oxygen. Mineral acids most likely are so named because they
were initially produced from minerals existing in naturally occurring ores.

TABLE 8.1 Relative Strengths of Some Common Acids in

Water

NAME OF ACID CHEMICAL FORMULA

Perchloric acid HCI04(aq)

Sulfuric acid H2S04’aq)

Hydrochloric acid HCl(aq)

Nitric acid HN03(aq)

Phosphoric acid H3P04(aq)
Nitrous acid HN02(aq)

Hydrofluoric acid HF(aq)
Acetic acid CH3COOH(aq)
Carbonic acida C02(aq)
Hydrocyanic acid HCN(aq)
Boric acid H3B03(aq)

‘The chemical form I f b . ‘d sometimes appears in the literature as H2COJ{aq). An acid having this che . u a o car onic ac1 h 1 1 f I f b · ‘d · m1cal compo ‘ti h b Isolated or identified. The c em ca ormu a o car on1c ac1 1s co s1 on, owever has never een d .
rrectly denot d C ‘ . h d’ th fact that carbonic acid has never been dlscovere , solutions of carbon d e as 0 2(a q) . Notw1t stan rng e

loxlde In water are acidic in nature.

strong acid Any acid
that predominantly
forms hydrated hydro-
gen ions when dis-
solved in water

strong base Any base
that predominantly
forms hydrated hydrox-
ide ions when dissolved
in water

weak acid Any acid
that predominantly
retains its molecular
identity when dissolved
in water

weak base Any base
that predominantly
retains its unit identity
when dissolved in
water

mineral acid Any
inorganic acid, chiefly
hydrochloric acid,
sulfuric acid, nitric
acid, perchloric acid,
phosphoric acid, and
hydrofluoric acid

Chapter 8 Chemistry of Some Corrosive Materials 273

organic acid (carboxylic
acid) An organic
compound containing
one or more of the
group of atoms

0
I

I

-c
\
OH

oxidizing acid Any
acid capable of reacting
as an oxidizing agent

nonoxidizing acid Any
acid incapable of
reacting as an
oxidizing agent

concentrated acid The
term routinely applied
to the commercially
available form of an
acid containing the
greatest concentration
of the substance

diluted acid Any form
of an acid that has
been produced by mix-
ing a concentrated acid
with water

pH A numerical scale
from O to 14 used to
quantify the acidity of
alkalinity of a solution
with neutrality indi-
cated as 7

acidic The property of
aqueous solutions that
have a pH ranging
from O to 7; the prop-
erty of any substance
that corrodes steel or
destroys tissue at the
site of contact

basic (caustic) The
property of aqueous
solutions that have a pH
rang ing from 8 to

14

alkaline Basic, as
opposed to acidic; an
aqueous solution or
other liquid whose pH
is greater than 7

The mineral acids are distinguished from organic acids, or carboxylic acids
stances whose molecules usually possess carbon, hydrogen, and oxygen atoms ortl sub.
organic acids have molecular structures that contain the following group of atoms: y, All

0
II – c
\
OH, or – COOH.

Acetic acid is the only organic acid noted in this chapter, but in Section 13.6, we will v· .
other organic acids. Collectively, they are weak acids. lSJt

8.2-C OXIDIZING AND NONOXIDIZING ACIDS
An acid chemically reacts as either an oxidizing acid or a nonoxidizing acid. An oxidizing acid
participates in chemical reactions as an oxidizing agent. A nonoxidizing acid participates in a
chemical reaction by some means other than oxidation.

Hot, concentrated sulfuric acid, nitric acid, and perchloric acid are oxidizing acids, but
hydrochloric acid, hydrofluoric acid, phosphoric acid, and acetic acid are nonoxidizing acids.
The degree to which the oxidizing acids corrode depends on how powerfully they participate
as oxidizing agents. We note this characteristic when we examine their individual properties.

8 .2-D CONCENTRATED AND DILUTED ACIDS
Chemists often refer to an acid as either diluted or concentrated. When they refer to a
concentrated acid, chemists generally mean the commercially available acid that has the
greatest concentration. When referring to a diluted acid, they mean a solution produced
by adding water to the concentrated acid.

This is not meant to imply that water is absent from a concentrated acid. A concentrated
acid may actually contain some amount of water. For example, concentrated hydrochloric
acid consists of approximately 36% to 38% hydrogen chloride by mass in water; 62% to
64 % of the solution is water. Diluted hydrochloric acid is any solution that results when addi-
tional water is added to this concentrated acid. Although concentrated hydrochloric acid is a
corrosive material, diluted hydrochloric acid may or may not exhibit corrosiveness depending
on its strength. When highly diluted with water, all acids lose their corrosive charactet

8.3 THE pH SCALE
The pH is a number ranging from 0 to 14 that denotes the acidity or alkalinity of an aqueous
solution. Aqueous solutions of substances that have a pH less than 7 are said to be acidic.
Let’s consider a simple example. In pure water, there is a very small hydrogen ion concentra·
tion derived by the dissociation of the water molecules. This is represented as follows:

H20(/) tt+(aq) + OH-(aq)
Water Hydrogen ion Hydroxide ion

When the hydrogen ion concentration in pure water is determined experimentally, we find
that it is only 0.0000001 (or 10-7) moles/liter. Instead of writing all these zeros, we expret
this concentration by indicating that the pH equals 7; that is, the pH is the de?ree_ of t0~
negative exponent. When the hydrogen ion concentration of an aqueous solut10n

15 O.
(or 10-2) moles/liter, the pH of the solution equals 2. .

Aqueous solutions having a pH greater than 7 are referred to as basic, cau5tic,8°;
alkaline. Because water is neither acidic nor basic, the pH of pure water is 7. Table ·
lists the pH values of some common solutions and mixtures. .

A unit change in a pH value represents a 10-fold difference in the hydrogen ion con;5
tration of a solution, and a difference of two pH units represents a 100-fold difference.

274 Chapter 8 Chemistry of Some Corrosive Materials

d

TABLE 8.2

Limewater, Ca(OH)i
Household ammonia

Milk of
magnesia

Blood——-1

14

1
13
12

11 Increasingly
10 basic

9

8
Pure water—-….J…_7—— — — —- —– –Neutral———– -Tap water——J

6
Coffee——-1-5

Wine— – –~
Vinegar——
Lemon juice•– —1
Gastric juice——,

4
3
2
0

Increasingly
acidic

j
means that the hydrogen ion concentration of an aqueous solution having a pH of 4 is 100
times greater than the hydrogen ion concentration of a solution having a pH of 6; and it is
1000 times greater than one having a pH equal of 7. In everyday practice, we say that a solu-
tion having a pH of 4 is 100 times more acidic than a solution having a pH of 6 and 1000
times more acidic than a solution having a pH of 7. Also, a solution with a pH of 8 is 10
times as alkaline as one with a pH of 7; a solution having a pH of 9 is 10 times as alkaline as
one having a pH of 8 and 100 times as alkaline as one having a pH of 7; and so on.

The pH is frequently determined by means of an electrometric apparatus called a pH
meter. The pH meter illustrated in Figure 8.2 is a voltage-measuring device that is connected

/

FIGURE 8 .2 The pH of an aqueous solution is
determined by using a pH meter. The user
immerses the electrodes in a sample of the solu-
tion, whose pH is read on the display monitor.
(Courtesy of Mettler-Toledo International, Inc.,
Columbus, Ohio. )

Chapter 8 Chemistry of Some Corrosive Materials 275

A compound in
which the hydrogen ion
from an acid has been
substituted with a
metallic ion

y
to an electrode whose tip is immersed in a solution. The pH of the solution is r dil
mined by simply reading a display monitor. ea Y deter,

8 .4 PROPERTIES OF ACIDS AND BASES
All acids are associated with certain common properties. They taste sour; the
indicator dyes to change to identifiable colors; and they react with bases to fo; cause
and water. In contrast, bases taste bitter; they feel slippery; they also cause the co7 salts
indicator dyes to change to identifiable colors; and they react with acids to for:::~!
and water. ts
. Acids a_nd bases_ can be readily diff~rentiated froi:n ~ne another b! the colors the
impart to pieces of litmus paper. Litmus 1s a common md1cator dye derived from cert .Y
lichens, any of a group of mosslike plants. A solution of litmus is used to impregn: tn
strips of paper that are subsequently dried. Individual strips are moistened with an aqu:~
ous solution of an acid or a base. Acids turn the litmus paper red, and bases turn the lit-
mus paper blue.

When acids and bases chemically interact, they neutralize each other. An example of
a neutralization reaction is represented by the following equation:

HCI(aq) + NaOH(aq) NaCl(aq) + H20 (l)
Hydrochloric acid Sodium hydroxide Sodium chloride Water

The compou-nd whose formula is listed to the immediate right of the arrow is called a salt.
Any compound in which the hydrogen in an acid has been replaced by a metallic ion is a
salt. Na Cl is the chemical formula of sodium chloride, which we commonly know as ordi-
nary table salt. It has properties that are dissimilar from those of both hydrochloric acid
and sodium hydroxide.

8.5 THE ANHYDRIDES OF ACIDS AND BASES
When a metallic or nonmetallic element combines with oxygen, the compounds produced
are metallic oxides and nonmetallic oxides, respectively. Sodium and calcium are two
examples of metals that burn in oxygen to form their corresponding metallic oxides.

4Na(s) + 02(g) 2Na20(s)
Sodium Oxygen Sodium oxide

2Ca(s) + 02(g) —–+ 2CaO(s)
Calcium Oxygen Calcium oxide

Sulfur and phosphorus are two ~xamples of nonmetals that burn in oxygen to form their
corresponding nonmetallic oxides.

Ss(/) + 80 2(g) —–+ 8S02(g)
Sulfur Oxygen S ulfur d ioxide

Phosphorus O xygen Tetrap hospho ru s hexoxide

A metallic oxide reacts with water to produce a base. These combination reactions
are denoted as follows:

Na20(s) + H20 (/) —–+ 2NaOH(aq)
Sodium ox ide Water Sodium hydroxide

CaO(s) + H20(/) —–+ Ca(OH)i(aq)
Calcium oxi de Water Calc ium hydro xide

Chapter 8 Chemistry of Some Corrosive Materials

TABLE 8.3 Acidic and Basic Anhydrides

CHEMICAL CHEMICAL
ANHYDRIDE FORMULA ACID/BASE FORMULA
Dinitrogen trioxide N203 (g ) Nitrous acid HN0 2(aq)
Din itrogen pentoxide N20 5 (g) Nitric acid HN03(aq)
sulfur dioxide S0 2(g) Sulfurous acid H2S0 3(aq)
sulfur trioxide S03(g) Sulfuric acid H2S 0 4(aq)
Tetraphosphorus hexoxide P405(s) Phosphorous acid H3P0 3(aq)
Tetraphosphorus decoxide P40 1o(s) Phosphoric acid H3P04(aq)
calcium oxide CaO(s) Calcium hydroxide Ca(OH)z(aq)
Magnesium oxide MgO (s) Magnesi um hydroxide Mg(OH)z(aq)
Potassium oxide K2 0 (s) Potassium hydroxide KOH(aq )
sodium oxide Na20 (s) Sodium hydroxide Na OH(aq)

A nonmetallic oxide reacts with water to produce an acid . These combination reactions
are represented by the following equations:

S 0 2(g) + H20(l) – H 2S03(aq)
Sul fu r di ox ide Wate r Sul fu rous acid

Te traphos phoru s hexox ide Water Phosphoro us aci d

The word anhydride refers to a substance from which the elements of water have
been extracted. It is either a metallic or a nonmetallic oxide. A metallic oxide that com-
bines with water to produce a base is called a basic anhydride, and a nonmetallic oxide
that combines with water to produce an acid is called an acidic anhydride. Sodium oxide
and calcium oxide are examples of basic anhydrides, and sulfur dioxide and tetraphos-
phorus hexoxide are examples of acidic anhydrides. Some common acids and bases and
their respective acidic and basic anhydrides are listed in Table 8.3.

Any
metallic or
nonmetallic oxide

basic anhydride Any
metallic oxide that
chemically combines
with water to produce
a base

acidic anhydride Any
nonmetallic oxide that
chemically combines
with water to produce
an acid

SOLVED EXERCISE 8.1

Write equations for th e followin g chemical phenomena :

(a) Bubbles of hydrogen are generate d wh en small chu nks of metallic calc ium are dropped into an aqueous
solution of hydrochloric acid .

(b) A surface coating of zinc oxide is rem oved by an aq ueous solution of sulfuric acid .
(c) Bubbles of carbon dioxide are generated w hen potassium carbonate is mixed into an aqueous solution

of phosphoric acid.

Solution: The phenomena in (a), (bl, and (cl are rep re sentative of t he chemica l reactions of ac ids w ith metals,
metallic oxides, and metallic carbonates, respective ly.

(a) Acids react with common metal s other than coppe r, sil ver, gold, and mercury to produce hydrogen and
a salt of the metal . Conseque ntly, metallic ca lcium reacts w ith hydrochloric acid to produce hydrogen
and calcium chloride according to the fo ll owing equation :

Ca(s) + 2HCl(aq) —–> CaCl2(aq) + H2(g)
Calcium Hydrochloric acid Calcium chlo ride Hydrogen

Chapter 8 Chemistry of Some Corrosive Materials 277

/’

I
I

I

I
I I

pickling The combina-
tion of chemical reac-
tions associated with
removing impurities
from the surfaces of
metals by immersing
them in an acid bath

(b) Acids react wit h meta llic oxi des to prod uce w ater an d a salt of the metal. Consequently, zinc OXid
acts with sulfuric aci d to produce zi nc sulfate an d w at er. ere.

ZnO(s) + H2S0 4(aq) —> ZnS04(a q) + H20(/)
Zi nc oxide Sulfuric acid Zinc sul fa te Water

(c) Acids rea ct with meta llic ca rbonates to pro duce carbon dioxide, water, and a salt of the metal C
d h h . ‘d d . on sequently, t he reaction bet ween potassi um carbonate an P osp one aci pro uces carbon dioxid;

water, and potassium phosphate. ‘

3K2C03(S) + 2H3P04(aq) —> 3C Oz(g) + 3 Hz 0 (/) + 2 K3 P0 4(aq)
Potassium carbonate Phosphoric acid Ca rbon dioxi de Water Potassium ph osph ate

8.6 ACIDS AND BASES AS CORROSIVE MATERIALS
Acids act as corrosive materials by reacting with metals, metalli~ oxid~s, metallic carbon.
ates, and skin tissue. Bases act as corrosive materials by reactmg with metals and skin
tissue. We consider these phenomena separately.

8 .6-A REACTIONS OF ACIDS AND METALS
Diluted acids react with all the commonly encountered metals ~ther than copper,
silver, gold, and mercury. These are simple displacement react10ns that produce
hydrogen and a salt of the metal. Two examples of such reactions are illustrated by
the following equations:

Mg(s) + 2HCl(aq) – MgClz(aq) + Hz(g)
Magnesium Hydrochloric acid Magnesium chloride Hydrogen

2Al(s) + 3H2S0 4(aq) – Al2(S04))(a q) + 3Hz(g)
Aluminum Sulfuric acid Aluminum sul fate Hydrogen

Because acids and metals are chemically incompatible, it is unsafe to store acids in
metal containers. This is why nonbulk quantities of acids are usually stored in glass or
plastic containers. When they are stored in metal drums or pails, the containers must
be rubber-lined.

8 .6-8 REACTIONS OF ACIDS AND METALLIC OXIDES
Acids react with metallic oxides to form a salt of the metal and water. Examples of this
type of double-displacement reaction are illustrated by the following equations:

FeO(s) + 2HCl(aq) – FeC12(aq) + H20 (l)
lron(ll) ox id e Hydrochl oric acid Iron(II) chlo rid e Water

Aluminum oxide Nitric acid Al uminu m nit rate Wate r

An acid is sometimes beneficially used to remove metallic oxides and other impurities
from the surface of metals. When used in this fashion, the acid is commonly called pickle
liquor, and t?e ass?ciated p?enomenon is called pickling. The steel industry uses lar;~
volumes of pickle hqu~r durmg_the _manu~acture of such products as wire, ro~, nu_cs, :nd
bolts. The common acids used m pickle liquors are sulfuric acid, hydrochloric acid,
phosphoric acid.

278 Chapter 8 Chemistry of Some Corrosive Materials

S,6-C REACTIONS OF ACIDS AND METALLIC CARBONATES
·ds react with metallic carbonates to produce carbon dioxide water and a salt of the Ac1 f h . . , ,

rnetal. Examples O t ese reactions are illustrated by the following equations:
CaC03(s) + 2HCl(aq) – CaC J2(aq) + C0 2(g) + H 20(l) Calcium carb onme Hydroc hloric acid

Calcium chl oride Carbon diox ide Water

Z inc carbonate S ul furic aci d
Zinc su lfate Carbon dioxide Water

s.G-D REACTIONS OF ACIDS WITH SKIN TISSUE
The nature of the corrosiv~ effect caused by prolonged exposure of skin tissue to an acid
depends on the concentration of the acid. When the skin contacts a diluted acid, the site
of contact may appear only reddened, whereas exposure to a concentrated acid for the
same duration could cause the ~kin to blister. In the worst incidents, prolonged exposure
of the skin to a c_oncentrated acid causes irreversible tissue damage and permanent disfig-
urement at the site of co_ntact. In either situation, the skin tissue is said to be “burned,”
because its appearance visually resembles a thermal burn.

s.6-E REACTIONS OF BASES AND METALS
Three common metals react with the concentrated solutions of strong bases, namely, alu-
minum, zinc, and lead. During the chemical reactions, hydrogen and a complex com-
pound of the metal are ~roduced. The following equations illustrate the chemical behavior
of these three metals with a concentrated solution of sodium hydroxide:

2Al(s) + 6NaOH(aq) – 2Na3AI03(aq) + 3H2(g) Aluminum Sodium hydroxide Sodium aluminate Hydrogen
Zn(s) + 2NaOH(aq) – Na2Zn02(aq) + H2(g ) Zinc Sod ium hydroxide Sodium zincate Hydrogen
Pb(s) + 2NaOH(aq) – Na2Pb0 2(aq) + H2(g) Lead Sodium hydroxide Sodi um plumbite Hydrogen

The reaction between sodium hydroxide and aluminum is especially important when exam-
ining the corrosive nature that strong bases exhibit with metals.

8.6-F REACTION OF BASES WITH SKIN TISSUE
Aqueous solutions of bases corrode skin tissue in a fashion that is associated with the
concentration of the base. When skin is exposed to a diluted solution, it appears reddened
at the site of contact. Although wounds of this type heal rapidly, when the skin has been
exposed to a more concentrated solution of the same base, it becomes sticky, soapy, and
soft in texture. Prolonged exposure causes the development of deep wounds that turn
black and leathery in texture and are very slow to heal. The tissue damage may be irre-
versible and cause permanent disfigurement at the site of con_tact. . .
ca Ex~o.su~e of the eyes to solutions of caustic substances ~s part1cularl_y worrisome. It
0 us~s. IUJunous changes in the structure of the cornea, ultimately leadmg to complete
Pacification (clouding).

8
·7

SULFURIC ACID

Sulfuric acid is . 1 ‘d h h mical formula is H 2S04• It is an odorless, col-Orie . a mmera ac1 w ose c e .
1 ss, oily liqu’d h • d • imately twice that of water. mpure or spent

sulfuric acid i’s 61 avmgbal ek°:s1ty al pprAox ‘ndustrial grade of sulfuric acid is sometimes rown to ac m co or. n 1

Sulfuric acid

Chapter 8 Chemistry of Some Corrosive Materials 279

FIGURE 8.3 This lead-
acid storage battery con-
tains a group of individual
cells, each of which con-
sists of a lead plate and a
lead oxide plate immersed
in an aqueous solution of
sulfuric acid. The specific
gravity of the sulfuric acid
ranges from 1 .2 5 to 1 .30
and serves as an
electrolyte .

TABLE 8.4 Physical Properties of Concentrated Sulfuric Acid

Melting point 50°F (10°()

Boiling point 640°F (338°C)

Specific gravity at 68°F (20°C) 1.84

Vapor density (air= 1) 2.8

Vapor pressure at 68°F (20°C) <0.001 mmHg

Solubility in water Infinitely soluble

encountered as a clear-to-brownish-colored liquid. The brown color reflects the p
f h

. l . f res-
ence o dissolved salts. Some of the important p ysICa properties o sulfuric acid
noted in Table 8.4 . are

If we were to list chemical substances by the amounts produced and consumed annu-
ally within the United States, we would find sulfuric acid near the top of these lists for the
past five decades. In the United States alone, well over 40 million tons (36 million t) of
sulfuric acid are produced annually. Sulfuric acid is so important commercially that its
production and consumption rates have been used by economists to estimate the extent to
which a country has industrialized.

The layperson is generally aware of sulfuric acid through its use as the electrolyte in
the lead-acid storage battery shown in Figures 1.6 and 8.3. As previously noted in Section
7.2-G, this battery is the electrical source in virtually all motor vehicles. However, sulfuric
acid has countless other uses. In the chemical industry alone, sulfuric acid is used to man-
ufacture explosives, fertilizers, drugs, and dozens of other compounds-including other
acids . Given its widespread usage, sulfuric acid has been called the workhorse of the
industrial world. The popularity of its use implies that sulfuric acid is likely to be encoun-
tered more frequently than other corrosive materials when responding to emergencies
involving hazardous materials .

As first noted in Section 1.5-A, OSHA requires every manufacturer, distributor, and
importer of a chemical substance to ensure that appropriate hazard warnings are pro·
vided on their containers. For example, OSHA requires them to provide the GHS hazard
information on the label shown in Figure 8.4 when the label is affixed to containers of
concentrated sulfuric acid. The information written under the heading DANGER con·
sists of GHS hazard and precautionary statements . The symbols required by WHMIS
also are shown.

Positive terminal Negative terminal

Ventcaps – — —

Electrolyte solution
Cell connectors – .W.::~ ~;S::~-l (dilute sulfuric acid)

Positive electrode -++—a¼-l-_…111 Protective casing
(lead dioxide)

Negative electrode —-‘
(lead)

c,__ _____ Cell divider

280 Chapter 8 Chemistry of Some Corrosive Materials

SULFURIC ACID

@
UN

2795
, Sulfuric acid, (contains less than 51% acid)

DANGER
Keep out _of reach of children. May be harmful if swallowed. Causes severe skin burns and d .
F t I “f • h I eye amage. May be corrosive to metals. a a

1
,n a ed. Harmful to aquatic life.

Do not breathe furn • .
es, mist, vapors, or spray. Absorb spillage to

ire~en_t ;iaterial damage. Store in corrosion-resistant container or
al n h~it a resistant inner liner. Wear protective gloves protective c ot mg eye t · ‘

. , pro ect,on, and face protection. Wear respiratory protection.

FIRST-AID INSTRUCTIONS:

IF IN EVES: Rinse cautiously with water for several minutes. Remove
contac~ lenses, if present, and easy to do. Continue rinsing.
Immediately call POISON CENTER or doctor.

IF SWALLOWED: Immediately call POISON CENTER or doctor.

IF ON SKIN: Remove immediately all contaminated clothing.
Rinse skin with water.

Read Safety Data Sheet before use.

My Company
My Street

My Town, My State 00000
Telephone (000) 000-0000

8.7-A PRODUCTION OF SULFURIC ACID
Sulfuric acid is prepared at industrial plants by first burning sulfur to produce sulfur diox-
ide, and then oxidizing the sulfur dioxide further in the presence of a catalyst to produce
sulfur trioxide. This is the acidic anhydride of sulfuric acid. It reacts with water to form sulfuric acid.

However, sulfur trioxide does not unite with pure water readily. When sulfuric acid is
manufactured industriaily, the sulfur trioxide is absorbed into a solution of sulfuric acid
containing 97% sulfuric acid by mass instead of pure water. Sulfur trioxide readily dis-
solves in this sulfuric acid solution. The final solution boils at 640°F (338°C) at 14.7 psia
(!~1.3 kPa) and contains 98.3 % sulfuric acid by mass. In commerce, this solution is iden-
tified as concentrated sulfuric acid. Emergency responders may encounter it in a variety of
containers such as those illustrated in Figures 6.1 and 6.2.
8
‘
7
”
8

THE HAZARD ASSOCIATED WITH DILUTING
Wbe SULFURIC ACID WITH WATER . .
the en c?ncentrated sulfuric acid is diluted with water, considerable heat 1s re_leased to
alw nvironment. Because this reaction is highly exothermic, extreme caution must
illendes be exercised when diluting concentrated sulfuri~ aci~ ~ith water. The recom-
suJf d Practice · l 1 h ‘d · to water while stirrmg. When concentrated

Uric acid is d~sl to ds ~w yhpour t e act m .. localized boiling and violent spattering
1 ute m t e reverse manneL,

FIGURE 8 .4 This label
affixed to nonbulk con-
tainers of sulfuric acid
complies with OSHA regu-
lations published at 29
C.F.R . §1910 . 1200(f).

Chapter 8 Chemistry of Some Corrosive Materials 281

I
I
I
I

Oleum

oleum (fuming sulfuric
acid) Concentrated
sulfuric acid containing
additional dissolved sul-
fur trioxide

occur that results in the production of a fume. When inhaled, the sulfuric acid fum
pose the risk of inhalation toxicity. e can

8 . 7-C DEHYDRATING ACTION OF CONCENTRATED SULFURIC ACID
Concentrated sulfuric acid possesses a capability for extracting water from certain Ill .
als. In certain instances, it is even capable of extracting the elements of water. This tteri.
ability is especially strong with organic compounds. Upon their contact, carbon is a;:er
the only visibly remaining residue. It is for this reason that concentrated sulfuri

O
~n

completely destroys wood, textiles, and paper. This dehydrating phenomenon also~ acid
when concentrated sulfuric acid burns body tissues. cc11rs

The ability of sulfuric acid to extract water is put to beneficial use during many ch
ical manufacturing processes. The manufacture of the explosive nitroglycerin, for ex em.
ple, uses sulfuric acid catalytically to extract the elements of water from glycerol:~
nitric acid (Section 15.6). n

8. 7-D OXIDIZING POTENTIAL OF CONCENTRATED SULFURIC ACID
Hot, concentrated sulfuric acid reacts as a strong oxidizing agent. For example, copper,
carbon, and lead are oxidized by hot, concentrated sulfuric acid as follows:

Cu (s) + 2H2S04( cone) CuS04(aq) + S02(g ) + 2H20(g)
Copper Sulfuric acid Copper(II) sulfate Sul fur dioxide Water

C(s) + 2H2S04(conc) C02(g) + 2S02(g ) + 2H20(g )
Carbon Sulfuric acid Carbon dioxide Sul fur di oxide Water

Pb(s ) + 3H2S04( cone) Pb(HS04)2(s) + S02(g) + 2H20(g)
Lead Sulfuric acid Lead(II) bisulfate Sulfu r dioxide Water

When the concentrated acid is at room temperature, however, it reacts so slowly with
these elements that the oxidation is barely perceptible.

8.7-E ILL EFFECTS CAUSED BY INHALING THE VAPORS, MISTS,
AND FUMES OF SULFURIC ACID

The repeated inhalation of sulfuric acid vapors, mists, and fumes by workers in occupa-
tional settings has been linked with the onset of larynx, paranasal sinus, and lung cancer.
These airborne forms of sulfuric acid are generated during the manufacture and use of
sulfuric acid, especially the use of the acid for pickling. Given its potential to cause cancer,
all work with sulfuric acid should be conducted only within a workplace that provides
adequate ventilation.

8 .7-F WORKPLACE REGULATIONS INVOLVING SULFURIC ACID
In the workplace, OSHA requires employees to limit employee exposure to a maximum sulfuric
acid vapor concentration of 1 milligram/cubic meter, averaged over an 8-hour workday.

8 .7-G OLEUM (FUMING SULFURIC ACID)
Sulfur trioxide dissolves in concentrated sulfuric acid, producing a thick, fuming yello~
liquid. When this liquid contains a higher proportion of sulfur trioxide than is fou nd 1.0

ordinary sulfuric acid, the resulting material is called oleum, or fuming sulfuric acid. T~s
acid is available commercially with varying concentrations of sulfur triqxide up to 99,9 ~d
Although oleum was formerly used in the petroleum refining industry, hydrofluoric ac~
(Section 8.11) now serves the same purpose. Today, oleum is used primarily within t e
chemical industry.

282 Chapter 8 Chemistry of Some Corrosive Materials

TABLE 8.5 Shipping Descriptions of Sulfuric Acid

FORM OF SULFURIC ACID

Sulfuric acid (contains less than 51 % sulfuric
acid)

Sulfuric acid (contains more than 51 % sulfuric
acid)

SHIPPING DESCRIPTION•

UN2796, Sulfuric acid, 8, PG II

UN1830, Sulfuric acid, 8, PG II

sulfuric acid, spent UN1832, Sulfuric acid, spent, 8, PG 11 ———-+~__:_:__:_ ___ ……:…_ __ -::-::–:—
Su If uric aci d, fuming (contains less than 30% UN1831 , Sulfuric acid, fuming, 8, PG I

sulfur trioxide) —————1————-:–:::-:-:–::-=–:-
Sulfuric acid, fuming (contains 30% or more UN1831, Sulfuric acid, fuming, 8, (6.1), PG I
sulfur trioxide) (Poison – Inhalation Hazard, Zone B) __________ L…:___:_:_ _________ —-:-

‘W hen shippers know the actual concentration of sulfuric acid or sulfur tr ioxide in the acid that Is transported,
DOT requires them to identify the concentration in lieu of a concentration range.

The chemical formula of oleum is often denoted as xH2SO 4 • yS 0 3, where x and Y are
rhe number of moles of sulfuric acid and sulfur trioxide, respectively. For example, oleum
that contains 1 mole of sulfur trioxide ( 80.1 g) for each mole of sulfuric acid (98.1 g) has the
fo rmula H 2S2O7, because in this instance, x = y = 1. Oleum containing 65% sulfur trioxide
by mass is expressed by the formula 4H2SO 4 • 9SO 3•

Because oleum contains dissolved sulfur trioxide, it has an elevated vapor pressure
compared to the value for concentrated sulfuric acid (<0.001 mmHg) . The vapor pres- sure for oleum varies according to the concentration of dissolved sulfur trioxide but ranges from 342 mmHg to 433 mmHg at 68°F (20°C). This means that fuming sulfuric acid poses the risk of inhalation toxicity.

Like sulfuric acid, oleum is a corrosive material. It severely burns the skin, which
generally heals to produce ugly scars. In addition, oleum spontaneously releases toxic
sulfur trioxide vapor, which poses the potential risk of inhalation toxicity. Consequently,
oleum should be stored and used only in a well-ventilated location.

8.7-H TRANSPORTING SULFURIC ACID
DOT regulates the transportation of four forms of sulfuric acid: a liquid having 51 % or
more acid; a liquid with less than 51 % acid; a spent sulfuric acid solution; and fuming
sulfuric acid. When these acids are offered for transportation, DOT requires their ship-
pers to provide the relevant shipping description shown Table 8.5 on the accompanying
shipping paper. The Hazardous Materials Table at 49 C.F.R. § 172.101 lists several con-
centrations of sulfuric acid . DOT requires shippers to parenthetically include an appro-
priate modifier like “contains” or “containing” between the shipping name and the
hazard class or following the shipping description. All other labeling, marking, and plac-
arding requirements apply.

S.8 NITRIC ACID
Nitric acid is second among the acids most commonly used throughout the United

~.1Y Slates. It is the raw material used for the manufacture of ammonium nitrate fertilizers ,
oQ ~ explosives, dyes perfumes drugs and nitrated organic compounds . Its use is also

17,
1J req · ‘ ‘ ‘

.il l’ uired for the production of pat ent leather and related fabrics. The chemical for-
~~1 ¥ lllula of nitric acid is HN0 3 . Some of its important physical properties are provided ,,II” in 1’able 8.6 .

Nitric acid

Chapter 8 Chemistry of Some Corrosive Materials 28;

TABLE 8.6 Physical Properties of Concentrated Nitric Acid

Melting point -44°F (-42°C)

Boiling point 187°F (86°C)

Specific gravity at 68°F c20°c) 1.50

Vapor density (air= 1) 3.2

Vapor pressure at 68°F (20°C) 47.9 mmHg

Solubility in water Infinitely soluble

Pure nitric acid is a colorless liquid. It is encountered commercially in concentrat d
and diluted forms. Concentrated nitric acid is an aqueous solution consisting of 68.2~
nitric acid by mass. All concentrations containing less than 68.2 % acid are forms 0;
diluted nitric acid.

When encountered, nitric acid is often yellow to red-brown in color, which indicates
that nitrogen dioxide is present. Nitrogen dioxide is a red-brown gas produced by the
slow decomposition of nitric acid, a reaction catalyzed by sunlight.

4HN03(l) 4N02(g) + 2H20(l) + Oz(g) Oxygen
Nitric acid Nitrogen dioxide

Water

8.8-A PRODUCTION OF NITRIC ACID
Almost all nitric acid is industrially manufactured from ammonia by means of a series of
reactions. Gaseous ammonia is first mixed with about 10 times its volume of air, and then
exposed to platinum gauze. The platinum increases the rate of the reaction that converts
ammonia into nitric monoxide (NO ). Then, additional air is permitted to enter the reac-
tion system so the nitrogen monoxide can be further oxidized to nitrogen dioxide.

4NH3(g) + 50z(g) 4NO(g) + 6H20(g)
Water

Ammonia Oxygen Nitrogen mo nox ide

2NO(g) + Oz(g) 2N02(g)
Nitrogen monoxide Oxygen Nitrogen dioxide

The nitrogen dioxide is then reacted with water to produce nitric acid.

3N02(g) + H20(l) 2HN03(l) + NO(g)
Nitrogen dioxide Water

Nitric acid Nitroge n monoxide

The excess nitrogen monoxide produced in this reaction is recycled through the system,

/

8.8-B OXIDATION OF METALS BY NITRIC ACID
Like hot, concentrated sulfuric acid, nitric acid is an oxidizing acid, even when it is diluted 1
with water at room temperature. When metals are chemically attacked by nitric acid, theY
are oxidized to their corresponding positive ions and the nitric acid is reduced to one or
more of the following: nitrogen, nitrogen monoxide, nitrogen dioxide, dinitrogen mono”·
ide, or the ammonium ion. Nitric acid reacts with some metals to form each of these
products under specific conditions. For example, it reacts with zinc to form nitrogen,
nitrogen ~onoxide, nitrogen dioxide, dinitrogen monoxide, or ammonium nitrate in sW
arate reactions.

284 Chapter 8 Chemistry of Some Corrosive Materials

5Z n(s) + 12HNO 3(aq) —-,. 5Zn(N O 3)z(aq ) + 6 H 2O (/) + Nz(g)
Zinc N itric acid Zinc ni trate Wate r N itrogen

3Zn(s) + 8HNO3(aq) —-,. 3Zn(N O 3)z(aq) + 4HzO([) + 2NO(g)
Zinc Nitric ac id Zinc nilrate Wate r N itroge n monoxide

Z n(s) + 4H NO3(co11 c) —-,. Zn(NO3)z(aq) + 2H2O(/) + 2NOz(g)
Zinc N itri c acid Zinc nitrate Water N itroge n d iox ide

4Zn(s) + I 0HNO3(aq) – 4 Z n(NO3)z(aq) + 5H2O (/) + N2O(g)
Zinc Ni tric ac id Z i nc nitrate Wate r Dini trogen m o nox ide

4zn(s) + I 0HNO3(aq) – 4Zn(NO3)z(a q) + 3H2O(/) + NH4N O 3(aq)
Zinc N itric ac id Z inc nitra te Wate r Ammonium nitrate

• rhe combination of these reactions that defines the corrosivity of nitric acid.
It is When nitric acid oxidizes a metal, the most common products formed are nitro-
en monoxide and nitrogen dioxide. In general, diluted nitric acid oxidizes metals to

g roduce nitrogen monoxide, and concentrated nitric acid oxidizes metals to produce P d. .d ·rrogen wx1 e.
ni On occasion, chemists use a nitrating solution to oxidize metals that are ordinar-
ily considered unreactive . . T?e most common solution used for this purpose is a 1 :3
mixture of concentrated mtnc and hydrochloric acids called aqua regia. It is one of a
limited number of mixtures known to react with metallic gold. The nitric acid oxi-
dizes the hydrochloric acid, as follows:

HN03(aq) + 3HCl(aq) – NOCl(g) + C l2(g) + 2H20(/)
Nitric acid Hydrochloric acid Nitrosyl chloride Chlorine Water

Nitrosyl chloride has a reddish-yellow color; hence, aqua regia is also reddish-yellow.

8.8-C OXIDATION OF NONMETALS BY NITRIC ACID
Hot nitric acid corrodes nonmetals. For example, carbon and sulfur are oxidized by hot,
concentrated nitric acid as depicted by the following equations:

C(s) + 4HN03(conc) –+ C02(g) + 4N02(g) + 2H20([)
Carbon Nitric acid Carbon dioxide Nitrogen di oxide Water

Ss(s) + 48HN03(conc) ._ 8H2S04(l) + 48NOz(g) + 16H20([)
Sulfur Nitric acid Sulfuric acid Nitrogen diox ide Water

8.8-D OXIDATION OF ORGANIC COMPOUNDS BY NITRIC ACID
Nitric acid oxidizes many flammable organic compounds, sometimes at explosive rates.
This results in their subsequent ignition. For example, the organic compounds turpentine,
a~etic acid, acetone, ethanol, nitrobenzene, and aniline react so vigorously when mixed
With hot, concentra ted nitric acid that they burst into flame.

8
·
8
·E REACTIONS OF NITRIC ACID WITH CELLULOSIC MATERIALS

Nitric ac·d · bl · · · f d l · d h c II . 1 ts capa e of initiating the spontaneous 1grut1on o woo , exce s10r, an ot er
r: ulosic materials, especia11y when these materials have been finely divided. It is for this
ar:son that bottles of nitric acid are not cushioned with a cellulosic materia l when they

transported.

8,8.F ILL
t-r . EFFECTS CAUSED BY EXPOSURE TO NITRIC ACID

Itr1c acid . . . h
their corrodes body tissues by reacting with the complex protems t at make up st

ructures. The exposure of n itr ic acid to the skin results in ugly, yellow burns that

aqua regia A 1 :3 mix-
ture of concentrated
nitric acid and hydro-
chloric acid

Chapter 8 Chemistry of Some Corrosive Materials 285

heal very slowly. The chemistry associated with this phenomenon involves the
of a yellow-brown substance called xanthoproteic acid. The discoloration of thpri~Uction
cally wears away in two to three weeks. es lil typi.

7

SOLVED EXERCISE 8.2

Fuming nitric
acid

Metallic copper does not replace the hydrogen in nitric acid, but metallic copper does react with nit • .
these reactions_ the nitric acid reacts as ~n _oxidizing agent. What are the products of the reactions in w~:~tid . 1n
lie copper 1s ox1d1zed by concentrated nitric acid and diluted nitric acid? rnetal.

S~lution: Concentrated ~itric acid oxidizes metals to produce nitrogen dioxide, “:’hereas diluted nitric acid .
d1zes metals to produce nitrogen monoxide. The metal is oxidized to the copper(II) ,on. oxi.

Cu (s) + 4H NO3(conc) – Cu(N O3)2(aq) + 2NOz(g) + 2H2O(/) Copper Nitric acid Copper(/1) ni tra te Nitrogen dioxide Water
3Cu(s) + 8HN03(dil) – 3C u(NO3)2(aq) + 2NO(g) + 4H2O(/) Copper Nitric acid Copper(/1) nitrate Nitrogen monoxide Water

8.8-G FUMING NITRIC ACID
The oxides of nitrogen are readily soluble in concentrated nitric acid. When the acid contains
a higher proportion of nitrogen oxides than is contained in ordinary nitric acid, the resulting
material is called fuming nitric acid, of which there are two varieties:

Red fuming nitric acid contains more than 85% nitric acid, less than 5% water, and
from 6% to 15% nitrogen oxides. Red fuming nitric acid containing 70% acid and
6% to 15% nitrogen oxides has a vapor pressure of 49 mmHg at 68°F (20°C}.
White fuming nitric acid contains more than 97.5% nitric acid, less than 2%
water, and less than 0.5% nitrogen oxides. It has a vapor pressure of 57 mmHg at
77°F (25°C). This second form is not widely encountered because it slowly reverts
to the red form.
Contact of the skin with fuming nitric acid is highly irritating. In addition, the red

form spontaneously releases toxic nitrogen oxide vapor, which poses the risk of inhalation
toxicity. For this reason, fuming nitric acid should always be segregated from other chem·
ical substances and stored and used in weII-ventilated locations.

8.8-H WORKPLACE REGULATIONS INVOLVING NITRIC ACID
In the workplace, OSHA requires employers to limit employee exposure to a maximum
nitric acid vapor concentration of 2 ppm, averaged over an 8-hour workday, and 4 ppm
for a short-term exposure.

8.8-1 TRANSPORTING NITRIC ACID
When shippers offer nitric acid or fuming nitric acid for transportation, DO_r
requires them to identify the appropriate substance with the relevant entry shown ~n
Table 8. 7 on the accompanying shipping paper. When carriers transport nitric acid
by highway or rail, DOT requires them to display the name NITRIC A CID on tW

0

opposing sides of the transport vehicle. All other labeling, marking, and placarding
requirements apply.

286 Chapter 8 Chemistry of Some Corrosive Materials

Representative Shipping Descriptions of Nitric Acid
CID Of NITRIC A SHIPPING DESCRIPTION

f0~NI ‘d other t han red fuming , w ith not
UN2031, Nitric acid, 8, PG I Nitric aci ‘ ]O’/o nitric acid

ore than
111 ‘d other than red fum ing, with more

UN2031, Nitric acid, 8, (5 .1), PG II •c ac1 , ‘d Nitrl % nitric acI
an 70

th .d mixtures, spent, with more than
UN1796, Nitrating acid mixtures, spent, 8, ·tric ac1 ‘d NI •tric acI (5.1), PG I o¾ n1

S .d mixtures, spent, with not more than
UN1826, Nitrating acid mixtures, spent, 8, PG 11 ·tric ac1 ‘d N1 ·tric acI o¾ n1

S ‘d mixtures w ith more than
UN1796, Nitric acid mixtures, 8, (5 .1), PG I itric ac1 . N ¾ nitric acid

so ‘d mixtures with not more than
UN1796, Nitric acid mixtures, 8, PG II Nitric ac1 _ . ¾ nitric acid

so df . ‘ h . . cid, other th~n r~ urning, wit not
UN2031, Nitric acid, 8, PG II N1tr1C ah 2oo/o nitri c acid moret an . .

•ng nitric acid with not more than
UN2032, Nitric acid, red fuming, 8, (5. 1, 6.1 ), Red fum1 . o¾ nitric acid PG I (Po ison – Inhalation Hazard, Zone B) 7

d f . · . “d other than re urning, with more
UN2031, Nitric acid, 8, (5.1 ), PG I Nitric ac1 ‘ . JOo/o nitric acid than

. ‘d other than red fuming, with not
UN2031, Nitric acid, 8, PG 11 N’tnc ac1 , . . 1 Oo/o nitric acid n,orethan 2

8,9 HYDROCHLORIC ACID
H drochloric acid is ~nother comm_ercially important acid. It is most familiar to the gen-
er~l public as a const1~ue~t of certam ~ous~hold cleaning products like Lysol Toilet Bowl
Cleaner. It also is the ltqmd used to mamtam the proper acidity of the water in residential

d public swimming pools.
an Outside the home, hydrochloric acid has many other uses. As a component of
pickle liquor, it is used for galvanizing, tinning, and enameling. In the food industry,
hydrochloric acid is used as a processing agent during the production of certain food
products such as corn syrup. It is used in the petroleum industry to activate petroleum
wells, and it is used in the chemical industry to manufacture and produce dozens of
important compounds. Hydrochloric acid is frequently encountered in educational and
research facilities, where it usually stored in nonbulk plastic containers like those
shown in Figure 6.1.

Pure hydrochloric acid is a colorless, fuming, and pungent-smelling liquid composed
1 of hydrogen chloride dissolved in water. The chemical formulas of hydrochloric acid and

hydrogen chloride are HCl(aq ) and HCl(g), respectively. Some physical properties of the
concentrated acid and its vapor are noted in Table 8.8.

‘ a,g,A PRODUCTION OF HYDROCHLORIC ACID
Hydrochloric acid is prepared by dissolving anhydrous hydrogen chloride in water. The
~~:ntra~ed ~cid contains from 36% to 38% hydrogen chlori~e by_ mass and is ~ol?rles~.

r. _Purity is not a factor the industrial grade of hydrochloric acid called muriatic acid 01
[en is d · ‘ · th · 1· htl 11 d tothe use · It 1s a dilute solution of concentration at 1s s 1g Y ye ow ue

Presence of metal impurities like iron salts.

Hydrochloric
acid

}
\,1\

Chapter 8 Chemistry of Some Corrosive Materials 28~

TABLE 8.8 Physical Properties of Hydrochloric Acid and Its Vapor

HCI (cone) HCI (g)

Melting point – 101 °F (-74°C) -174•F (114’C)

Boiling point 127°F (53°C) -121’F (-8S’C)

Specific gravity at 68°F (20°C) 1.18
1.27

Vapor density (air = 1) 1.3 1.3

Vapor pressure at 68°F (20°() 150 mmHg 30,780 mmHg

Solubilit in water y 85 /100 g g of H O at 68°F (20°C)
67% at 68′ 0 F (20 q

8 .9-B ILL EFFECTS CAUSED BY INHALING HYDROGEN CHLORIDE
The principal hazardous feature of hydrochloric acid is associated with inhaling th
hydrogen chloride vapor released spontaneously from the ~onc~ntra_ted acid. Hydroge~
chloride is a poisonous gas. When concentrated hydrochlonc acid spills or leaks from its
container, the pungent odor of its toxic vapor is immediately detectable. Because the
vapor is approximately one-fifth heavier than air, it lingers in low areas, where it can pose
a risk to health and safety.

When hydrogen chloride vapor is encountered, individuals experience the symptoms
noted in Table 8.9. In the worst situations, prolonged exposure to massive amounts of
hydrogen chloride causes pulmonary edema (Section 7.3-B), which can completely dete-
riorate the tissue cells within the respiratory tract and destroy its lining.

TABLE 8.9 Ill Effects Caused by Inhaling Hydrogen Chloride

HYDROGEN CHLORIDE (ppm) SYMPTOMS

1-5 Threshold limit for detection of smell

5-10 Mild irritation of mucous membranes, eyes, nose, and throat

35 Distinct irritation of mucous membranes, eyes, nose, and throat

5-100 Barely tolerable effects including severe coughing and panic;
possible injury to the bronchial region

1000 Danger of pulmonary edema after 24-hr exposure; potentially fatal

SOLVED EXERCISE 8.3
Use the data in Tables 8.4 an d 8.8 to determine whether each of the following aci ds poses the greater haza rd by
inhalation toxicity at 68°F (20°C) when all other factors are considered equally: (a) concentrated sulfuric acid or
concentrated hydroch loric acid; (b) oleum or concentrated hydrochloric acid.

Solution:
(a) To pose an inhalation toxicity hazard, the liq uid aci d must produce sufficient vapor at 68°F (20′ Cl to

cause illness or death when inhaled . In Table 8.4, the vapor pressure of concentrated sulfuric acid
15

listed as < 0.001 mmHg . This low val ue si gn ifies that vi rtually no vapor is produced at this temperature. Accordingly, exposure to concentrated sulfuric aci d poses a very low risk of inhalation toxicity. However, the vapor pressure of hydrochloric aci d is listed in Table 8.8 as 150 mm Hg . This elevated value indicates that when in haled, hydrochlori c aci d produces suffi ci ent vapor at 68•F (2o•c) to cause the ill effects noted in Table 8.9.

288 Chapter 8 Chemistry of Some Corrosive Materials

I

oieurn, or f~rning s~lfuric acid, has _ a ~aper pressure ranging from 342 mm Hg to 433 mm Hg at 68°F
(b) (Z0°C) since it contains f~ee s_ulfur trioxide. Hence, it poses a greater risk of inhalation toxicity than does

concentrated hydroch~oric acid . Non~:heless, _some caution must be exercised with the use of the phrase
“all other factors considered equally. _ In particular, sulfur trioxide is a cancer-causing substance whereas
hydrogen chlorid e is not. On ~his basis alone, health officials are likely to cons ider that oleum poses a
greater risk of inhalation tox1c1ty than does concentrated hydrochloric acid .

C REACTIONS OF HYDROCHLORIC ACID WITH
s.9· OXIDIZING AGENTS

d ochloric acid is chemically incompatible with oxidizing agents such as metallic chlo-
rlY r metallic dichromates, and metallic permanganates. These reactions result in the
races, . hl .

d Ction of toxic c orme. pro u
KC103(s) + 6HCl(conc) K Cl(aq) + 3H20(l) + 3Clz(g)

Poiassi urn chl orate Hydrochloric acid Potassium chloride Water Chlorine

K2Cr20 7(s) + l4HCl (conc) 2KCl(aq) + 2CrCI 3(aq) + 7H20 (/) + 3Clz(g)
Potassium dichromate Hydroc hloric acid Potassium chloride Chromium(HI) chlo ride Water Chl orine

2KMn04Cs) + 16HCl(conc) 2MnCI2(aq) + 2KCl(aq) + 8H20 (l) + 5C lz(g)
Poiassiurn permanganate Hydroc hl oric ac id Manganese(Il) chloride Potassiu m chlori de Water Chlorine

To reduce or eliminate the likelihood of an unwanted reaction between hydrochloric
acid and chlorine-producing pool chemicals, acid manufacturers often label their contain-
ers with a message like the following:

DO NOT STORE NEAR
CHLORINE-PRODUCING

POOL CHEMICALS

8.9-D ANHYDROUS HYDROGEN CHLORIDE
Anhydrous hydrogen chloride itself is a commercial chemical product that is prepared by
the direct combination of elemental hydrogen and chlorine.

H2(g) + Clz(g) 2HC l(g)
Hydrogen Chlorine Hydrogen chlolide

Hydrogen chloride is also produced as a by-product during the chlorination of organic
compounds.

8·9·E WORKPLACE REGULATIONS INVOLVING
HYDROGEN CHLORIDE t the Workplace OSHA requires employers to limit employee exposure to a maximum

Ydrogen chlorid~ vapor concentration of 5 ppm, which should not be exceeded during
any Pan f h 0 t e working exposure.

S,g.F TRANSPORTING HYDROCHLORIC ACID AND
ANHYDROUS HYDROGEN CHLORIDE

Do~ shippers offer hydrochloric acid or anhydrous hyd~o~en chlorid~ for transportation,
aeco reqwres them to provide the relevant shipping description show~ m Table 8._10 on the
rail tnpanying ship · Wh hydrogen chloride is transported m bulk by highway or
‘Iv ‘bo1 also re ~mg pap~r. en k the bulk packaging on two opposing sides with the

ords INZJ quires earners to mar d 1 din • 1 o.ALATION HAZARD. All labeling, marking, an p acar g reqwrements app y.

Anhydrous
hydrogen chloride

Chapter 8 Chemistry of Some Corrosive Materials 289

I I I

Perchloric acid

TABLE 8.10
Shipping Descriptions of Hydrochloric Acid
and Hydrogen Chloride

HYDOCHLORIC ACID/HYDROGEN CHLORIDE SHIPPING DESCRIPTION

Hydrochloric acid

Hydrogen chloride, anhydrous

Hydrogen chloride, cryogenic liquid

8.10 PERCHLORIC ACID

UN1789, Hydrochloric acid, 8, PG 11

or
UN 1789, Hydrochloric acid, 8, PG 111

UN1050, Hydrogen chloride, anhydrous 23 (Poison – Inhalation Hazard, Zone C} ‘ · ‘(B),

UN2186, Hydrogen chloride, refrigerated I’ .
2.3, (8), (Poison – Inhalation Hazard, Zone tjUid,

Perchloric acid is an acid used primarily by the chemical, electroplating, and incendiary
(fireworks) industries. Its chemical formula is HCl04 .

8 .10-A PRODUCTION OF PERCHLORIC ACID
Concentrated perchloric acid is prepared by distilling a mixture of potassium perchlorate 1
and sulfuric acid at reduced pressure (i.e., lower than atmospheric pressure). The chemical
reaction associated with its production follows:

Potassi um perchlorate Sulfuri c acid Perchloric ac id Potassium sulfate

The acid is a colorless, aqueous liquid having an approximate composition of 72% by
mass. This is the composition of the concentrated perchloric acid available commercially.
Although solutions of perchloric acid having an acid concentration greater than 72% are
known, they are not routinely encountered, because they are explosively unstable. Some
physical properties of concentrated perchloric acid are noted in Table 8.11.

8 .10-B THERMAL DECOMPOSITION OF PERCHLORIC ACID
Concentrated perchloric acid may be safely heated to 194°F (90°C), but above this tern·
perature, it is likely to explosively decompose as follows:

Perchloric acid Chlorine Oxygen Water

TABLE 8.11 Physical Properties of Concentrated Perchloric Acid

Melting point 0°F (-18°C)

Boiling point 397°F (203°C)

Specific gravity at 68°F (20°C) 1.70

Vapor density (air= 1) 3.5

Vapor pressure at 68°F (20°C) 6.75 mmHg

Solubility in water Very soluble

290 Chapter 8 Chemistry of Some Corrosive Materials

Although elemental aluminum is stable in the form of foil and sheets, alu :,
and powder are pyrophoric materials that pose the risk of fire and explosion ~~tun dust
num burns violently in air with an intensely bright, white and orange flame · e alutni.
mixture of aluminum oxide and aluminum nitride. producing a

4Al(s) + 30z(g) 2Al203(s)
Alnminum Oxygen Aluminum oxide

2Al (s) + N2(g) 2AIN(s)
Aluminum Nitrogen Aluminum nitride

These reactions may be initiated by the combustion of hydrogen, produced when th
and powder react with atmospheric moisture. e dust

2Al(s) + 3H20(/) Al203(s) + 3H2(g)
Aluminum Water Aluminum oxide

Hydrogen

Powdered aluminum burns spontaneously on contact with liquid oxygen. Ahunin
oxide is the sole product of combustion. UJn

The reactivity of aluminum powder is put to use in the formulations of many fir _
~arks, i~ whic~ the metal, when activated, burns to pro~uce a bri_lliant disp~ay of oran:e
light. It is also mcorporated into certain paints and varmshes for its decorative and heat-
reflective features; but consideration must be given to their use, because these coatings
may behave as flammable solids once the paint solvent has evaporated. Aluminum pow-
der is also a component of solid rocket fuels, in which it is mixed with ammonium nitrate
and ammonium perchlorate. The mixture of powdered aluminum and ammonium nitrate
is an explosive called ammonal.

The catastrophe of the German dirigible Hindenburg may have been linked with
the combustion of aluminum powder. The exterior surface of the dirigible consisted. of
a cloth cover impregnated with a doping mixture of aluminum powder and ferric
oxide. The presence of aluminum powder provided a surface having high reflectivity.
The cover was intended to serve an important purpose: The aluminum particles
reflected heat off the vessel and prevented the hydrogen from expanding. The prevail-
ing theory is that the aluminum powder first caught fire at an isolated location, per-
haps triggered by static electricity or lightning. Once initiated, the fire then rapidly
spread across the entire covering, ultimately igniting the reserves of hydrogen. The
resulting inferno consumed the vessel.

In circumstances where the temperature is substantially elevated compared with
the norm, even bulk aluminum acts as a fast-burning fuel. The skin of shuttle aircraft,
for example, must be armored with heat shielding to protect the shuttle when it reen·
ters Earth’s atmosphere from outer space, experiencing temperatures in excess of
3000°F (1650°C). If this shielding is pierced in any way, the underlying aluminum
becomes superheated. Aluminum melts at 1220°F (660°C) and vaporizes at 4221°F
(2327°C). At these temperatures, aluminum fires occur when oxygen is available to
support the combustion.

In 2003, the space shuttle Columbia disintegrated on reentry into Earth’s atmosphere,
killing the seven astronauts onboard. The shuttle was covered with more than 20,00

0

interlocking ceramic tiles designed to protect the aluminum alloy shell from the heat

0
~

reentry. Experts who examined debris from the accident wreckage observed droplets
0

aluminum and stainless steel. This observation suggests that the cause of the accident w~s
linked with the loss of the thermal protective system on the left wing, especially alo~g its
leading edge. Without its protective covering, the underlying aluminum alloy most likelY
burned, ultimately destroying the entire shuttle.

322

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

E IVIETALLIC ZINC
9 3· d · ·1 b • –

5
produce pnman Y Y means of the following two-step thermal process·

z;inC I . . .

11
First, the zinc sulfide ore sphaler,te, or zinc blende, is roasted in air to produce zinc oxide.

2ZnS(s) + 302(g) – 2ZnO(s) + 2S02(g)
Zinc sulfide Oxygen Zinc oxide Sulfur dioxide

11
Then, the oxide is reduced with carbon monoxide.

ZnO(s) + CO(g) – Zn (g) + C02(g)
Zinc oxide Carbon monoxide Zinc Carbon dioxide

The zinc vapor _produced by the reaction is then distilled, condensed, and cast into ingots.
The zinc depos~ts on the walls of the distillation apparatus as a gray, finely divided pow-

d known as zmc dust. er uf . The zinc man acturmg process is complicated by the presence of the metal impuri-
ties silver, lead, copper, arsenic, antimony, and manganese, all of which occur naturally in
sphalerite. These ~etals are rem?ved by a combination of chemical processes. The manu-
facturing process 1s also complicated by the simultaneous production of the pollutant
sulfur dioxide (Section 10.12), which must be scrubbed from the off-gas plume generated
during the roasting process.

Metallic zinc is used for several purposes. The metal is coated on iron products to
protect them from corrosion by the air. This zinc-coated iron is said to be galvanized.
Zinc is also used as a component of several alloys; for example, zinc and copper are com-
bined in the molten state to produce brass. Metallic zinc is also used in the manufacture
of dry-cell batteries and a variety of structural materials. Zinc dust is a component of
certain primers and rust-resistant paints.

Zinc is hazardous only as its dust. Especially when it is hot, zinc dust is a pyrophoric
material that poses a fire and explosion hazard. It ignites spontaneously in air with a green
flame, producing zinc oxide as the sole combustion product.

2Zn(s) + 02(g) 2Zn0(s)
Zinc Oxygen Zinc oxide

The reaction may be initiated by the combustion of hydrogen, produced when the dust reacts
with atmospheric moisture.

Zn(s) + H20(/) ZnO(s) + H2(g)
Zinc Water Zinc oxide Hydrogen

9.3-F TRANSPORTING COMBUSTIBLE METALS
When shippers offer a combustible metal for transportation, DOT requires them to iden-
tify the appropriate material on the accompanying shipping paper. Some examples for
several representative combustible metals are listed in Table 9.5. DOT also requires ship-
pers and carriers to comply with all labeling, marking, and placarding requirements.

When molten aluminum is transported in bulk packaging by highway or rail, DOT
requires carriers at 49 C.F.R. § 172.325 to mark the packaging with the expression MOLTEN
ALUMINUM and the identification number 9260 on orange panels, white square-on-point
diamonds, or HOT markings. The following examples illustrate the nature of these markings:

Zinc metal
powder/dust

galvanize The process
of coating a metal with
a protective layer of
elemental zinc

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 323

TABLE 9.5

COMBUSTIBLE METALS SHIPPING DESCRIPTION
Aluminum, molten NA9260, Aluminum, molten, 9, PG I

Aluminum powder UN1309, Aluminum powder, coated, 4.1, PG 11
or
UN1396, Aluminum powder, uncoated, 4.3, PG 11 (Dan

Magnesium (with more than 50% magnesium in pellets
turnings, or ribbons) ‘

UN1869, Magnesium, 4.1, PG Ill

Magnesium alloys (with more than 50% magnesium in UN1869, Magnesium alloys, 4.1, PG Ill
pellets, turnings, or ribbons)

Magnesium granules (particle size not less than 149 microns) UN2950, Magnesium granules, coated, 4.3, PG Ill (Dan
When Wet) Qerous

Magnesium powder UN1418, Magnesium powder, 4.3, (4.2), PG I (Dangerous
When Wet)
or
UN1418, Magnesium powder, 4.3, (4.2), PG 11 (Dangerous
When Wet)
or
UN1418, Magnesium powder, 4.3, (4.2), PG 111 (Dangerous
When Wet) -Titanium powder UN2546, Titanium powder, dry, 4.2, PG I

Titanium (powder), wetted with not less than 25% water UN1352, Titanium powder, wetted, 4.1, PG II
(a visible excess of water must be present) (a) mechanically
produced, particle size less than 53 microns; (b) chemically
produced, particle size less than 840 microns

Titanium sponge granules UN2878, Titanium sponge granules, 4.1, PG Ill

Titanium sponge powders UN2878, Titanium sponge powders, 4.1, PG Ill

Zinc dust UN1436, Zinc dust, 4.3, (4.2), PG I (Dangerous When Wet)

Zinc powder UN1436, Zinc powder 4.3, (4.2), PG I (Dangerous When Wet)

Zirconium, dry (finished sheets, strip, or coil wire) UN2008, Zirconium, dry, 4.1 PG Ill

Zirconium powder, wetted with not more than 25% water UN1358, Zirconium powder, wetted, 4.1, PG II
[(a visible excess of water must be present) (a) mechanically
produced, particle size less than 53 microns; (b) chemically

· m’crons produced, particle size less than 840 1

9.4 ALUMINUM ALKYL COMPOUNDS
AND THEIR DERIVATIVES

aluminum alkyl • A
compound whose
molecules are composed
of an aluminum atom
covalently bonded to
three carbon atoms,
each of which is a
component of an

Organometallic substances are compounds whose molecules have one or more metal
atoms covalently bonded directly to a nonmetal atom. Examples of organometallic sub·
stances include the aluminum alkyls, whose molecules have an aluminum atom covalently
bonded to three carbon atoms. An example of an aluminum alkyl compound is triethyl-
aluminum, whose chemical formula is Al(CH2CH3)J, or Al(C2H5)).

alkyl group

CH2CH3
I

CH3CH2 – Al-CH2CH3
Triethylaluminum

(TEA)

324 Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

is instance, the ~lkyl grou~ is na~ed ethyl, which has the formula -CH2CH3. In the
Jo th ical industr~, tnethY1alummum is often designated as TEA. Its properties are repre-
chern ·ve of aluminum alkyl compounds.
eorau · I r ps of I · lk I I h I’d s rwo specia g ou . a ummum a yl compounds are the aluminum a ky a es

JUJllinum alkyl hydrides. These compounds are the halide and hydride derivatives
aod t JJJinum alkyl compounds, respectively, in which one or two halide or hydrogen
of au substitute for an alkyl group. Examples of these derivatives are diethylaluminum
at0~:de and diisobutylaluminum hydride, whose formulas are (C2H5 )zAICI and
chi~ ) cHCH2]zAIH, respectively.
[(CP 3 2

Cl H

I I

CH3CH2-Al – CH2CH3 (CH3)zCHCH2-AI – CH2CH(CH3h
Diethylaluminum chloride Diisobutylaluminum hydride

(DEAC) (DIBAH)

The alkyl group having the formula _(CH3)zCHCH2- is named isobutyl. In the che1?ical
. dustrY, these compou?ds are sometimes designated as DEAC and DIBAH, respectively.
;~ this section, we consider them as representative of the halide and hydride derivatives of
all aluminum alkyl ~ompounds. . .

Table 9.6 provides some physical properties of triethylaluminum, diethylalununum
hloride, and diisobutylaluminum hydride. Chemical manufacturers display the flame

;icrogram on la_bel~ affixed to containers holding the aluminum alkyls and their halide
and hydride derivatives.

g,4-A COMMERCIAL USES OF THE ALUMINUM ALKYL COMPOUNDS
AND THEIR DERIVATIVES

The aluminum alkyls are used by the chemical industry primarily as polymerization cata-
lysts, one of which is a mixture of titanium(IV) chloride and an aluminum alkyl. It is
called a Ziegler-Natta catalyst, after Karl Ziegler and Giulio Natta, the chemists who
first discovered its catalytic capability. Aluminum alkyl halides and aluminum alkyl
hydrides are also primarily used as catalysts in the chemical industry.

Aluminum alkyl compounds have also been used by the military, albeit rarely, as
incendiary agents. For example, triethylaluminum has been used as the active component
in flamethrowers. Trimethylaluminum has also been used to produce luminous trails in
the upper atmosphere for tracking the location of rockets.

Physical Properties of an Aluminum Alkyl Compound
TABLE 9.G and Two Metal Alkyl Derivatives

Melting point
Boiling point

Specific gravity
Vapor pressure
Flashpoint

Autoignition
temperature
‘At 3 mmHg (0.3 kPa).
bAt 68’F (20’C).
‘At 77’F (25’C).

TRIETHYLALUMINUM

-62°F (-52°C)

367°F (186°C)

0.837b

0.0147 mmHgb

-63°F (-53°C)

Spontaneously
flammable in air

DIETHYLALUMINUM DIISOBUTYLALUMINUM
CHLORIDE HYDRIDE

-121 °F (-85°C) -112°F (-80°C)

417°F (214°C) 237°F (114°C)a

0.961′ 0.798′

0.17 mmHg’

-9.4°F (-23°C)

Spontaneously Spontaneously
flammable in air flammable in air

Triethyl-
aluminum

Ziegler-Natta catalyst
Any of a group of

compounds produced
from titanium
tetrachloride and an
aluminum alkyl
compound that is used
mainly as a catalyst

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 325

I /I
: I

I I I I I
I/ I I Ill

i I
I I

111

I
I

I I

9 .4-B PROPERTIES OF THE ALUMINUM ALKYL COMPOUNos A
THEIR DERIVATIVES “‘~[)

The aluminum alkyl compounds and their derivatives are spontaneous!
b_le, pyrophoric, violently water-reactive, and highly toxic liquids. They y cornbllsr
cially available as individual compounds and solutions in which they are~~ comm/
organic solvents. When triethylaluminum, diethylaluminum chloride, and ~~~0 lved t’
aluminum hydride spontaneously ignite, their combustion reactions are re lisobllty~
as follows: Presented

2(C2H5)3Al(l) + 2102(g) Al203(s) + 12C02(g) + 15H20(g)
Triethylalurninum (TEA) Oxygen Aluminum oxide Carbon dioxide Water

2(C2HshAICl(l) + 1402(g) Al203(s) + 8C02(g) + 9H20(g) + 2BC!(g)
Diethylaluminurn chloride (DEAC) Oxygen Aluminum oxide Carbon dioxide Water Hydrogen chloride

2 [(CH3)iCHCH2hAIH(s) + 2702(g) Al203(s) + · I6C02(g) + 19H20 (g)
Diisobutylaluminum hydride (DlBAH) Oxygen Al uminum oxide Carbon dioxide Water

When triethylaluminum and diethylaluminum chlor~de react with water, the fl
mable gas ethane (Section 12.2) is produced as a hydrolysis product. a111•

Triethylaluminum (TEA) Water Aluminum hydroxide Ethane

Diethylaluminum chloride (DEAC) Water Aluminum hydroxide Ethane Hydrogen chloride

Diisobutylaluminum hydride, however, is a reducing agent. When it reacts with water, the
flammable gases isobutene and hydrogen are produced.

Diisobutylaluminum hydride (DIBAH) Oxygen Aluminum hydroxide Isobutene Hydrogen

When water is applied to these reactive substances, the gaseous hydrolysis prod-
ucts immediately burst into flame as they are generated. The considerable heat evolved
to the environment often triggers secondary fires. Bulk quantities of aluminum alkyl
compounds burn so vigorously and persistently that they pose an especially dangerous
risk of fire and explosion. The heat of combustion that evolves necessitates that fire-
fighters wear special protective gear like the silvers shown in Figure 9.4 when combat·
ing these fires. .

To prevent their accidental ignition, the aluminum alkyl compounds and their halide
and hydride derivatives often are stored within electrically grounded containers under an
atmosphere of nitrogen in a cool, well-ventilated area.

9.4-C TRANSPORTING ALUMINUM ALKYL COMPOUNDS
AND THEIR DERIVATIVES

When shippers offer an aluminum alkyl compound or a halide or hydride derivative for tr:·
portation, DOT requires them_ to id~ntify it with the proper shipping ~ame, “organomet F.R~
substance,” on the accompanymg shipper paper. The Hazardous Materials Table at 49 C. .
§172.101 lists several shipping names for organometallic substances. Because triethylal~:
num is both water- and air-reactive, its most appropriate shipping description is the followmg.

UN3394, Organometallic substance, liquid, pyrophoric, water-reactive (triethyl-
aluminum), 4.2, (4.3), PG I (Dangerous When Wet).

326 Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

FIGURE 9 .4 When responding to fires involving
aluminum alkyl compounds and their halide and .
hydride derivatives, firefighters should wear special
protective clothing such as alum1nized suits tha:
reflect heat and provide protection against bodily
contact with the reactive substances as they burn .
(Courtesy of Lakeland Industries, Inc., Ronkonkoma, New
York; Image © 2012, All Rights Reserved.)

FIGURE 9.5 When a carrier transports an alumi-
num alkyl compound or its halide or hydride deriva-
tive in an amount exceeding 1001 pounds (454 kg),
DOT requires SPONTANEOUSLY COMBUSTIBLE and
DANGEROUS WHEN WET placards to be displayed
on the transport vehicle . AKZX is the reporting
mark of AKZO Nobel Chemicals, Inc., Chicago, Illi –
nois, a distributor of triethylaluminum and other
class 4 compounds.

When transporting aluminum alkyl compounds or their halide or hydride derivatives,
shippers and carriers must also comply with all applicable labeling, marking, and placard-
ing requirements. Figure 9 .5 illustrates that DOT requires carriers to display DANGER-
OUS WHEN WET placards on the bulk packaging used for shipment regardless of the
amount transported.

When 387 gallons (829 L) of liquid diisobutylaluminum hydride is transported in a 400-gallon (857-L) portable
tank by highway:

(a) What sh ipping description does DOT require the shipper to enter on the accompanying shipping paper?
(b) How does DOT require the carrier to placard and mark the tank?

Solution:

(a) There are two regulations in Table 6.2 that are pertinent to preparing the shipping description . First,
when a hazardous material is described with a generic description in the Hazardous Materials Table
shippers must include the name of the substance in parentheses in the shipping description . Second:
when a hazardous material, by chemical interact ion with water, is liable to become spontaneously

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 327

ionic A
compound composed
of a metallic ion and a
simple or complex
hydride ion

Sodium hydride

flammable or give off flammable gases in dangerous quantities, the _w~rds “Dangerous Wh
must be included with the shipping description. Consequently, the shipping description of d” en ‘Net•
luminum hydride is entered on a shipping paper as follows: iisobu~la.

SHIPPING DESCRIPTION
(IDENTIFICATION NUMBER, PROPER SHIPPING NAME,
PRIMARY HAZARD CLASS OR DIVISION, SUBSIDIARY VOLU••,

_ _:_U::_N.::_IT:_:S:_–1-_.:_H::.:M~___:_::HAZ~ A_R_D_C_LA_S_S_O_R_D-:-IV_I_SI_O–::N,_A-:-:N_D_P_A-;-C-:K_IN_G_G_R_O_UP…:…)-+- (gal)’
1 portable tank x UN3394, Organometallic substance, liquid, pyrophoric, water-reactive 387 (diisobutylaluminum hydride), 4.2, (4.3), PG I (Dangerous When Wet)

(b) Since the amount transported exceeds 1001 pounds, DOT requires carriers to display side b .
SPONTANEOUSLY COMBUSTIBLE and a DANGEROUS WHEN WET placard on each side and eac~ side a
the cargo tank. Because the tank has a capacity of less than 1 OOO ~allo~s (3785 L), DOT requires t~: ~:
mark the tank with the identification number 3394 on two opposing si?es on orange panels, across the
center area of the SPONTANEOUSLY COMBUSTIBLE placards, or on white square-on-point diamond I ,

9.5 IONIC HYDRIDES
Approximately ten ionic hydrides are encountered commerciall!. T_hey are compounds
consisting of metallic ions bonded to simple or complex hydnde ions. Some metallic
hydrides are not ionic hydrides. For example, although tin(IV) hydride is a metallic
hydride, ·it is composed of molecules. Each molecule consists of a tin atom covalently
bonded to four hydrogen atoms. Its chemical formula is S~. ·

Ionic hydrides are used as powerful reducing agents by the chemical industry. They
can be classified according to their general chemical composition as simple ionic hydrides,
ionic borohydrides, and ionic aluminum hydrides.

9.5-A SIMPLE IONIC HYDRIDES
Simple ionic hydrides are compounds consisting of metallic ions bonded to hydride ions
(H-). They are lithium hydride, sodium hydride, calcium hydride, magnesium hydride,
and aluminum hydride, whose chemical formulas are LiH, NaH, CaH2, MgH2, and AlH3,
respectively. They are produced by reactions between the corresponding metal and hydro-
gen. For example, sodium hydride is a simple ionic hydride produced by the union of
sodium metal and hydrogen.

2Na(s) + H2(g) 2NaH(s)
Sodium Hydrogen Sodium hydride

9.5-B IONIC BOROHYDRIDES
Ionic borohydrides are ionic hydrides in which metallic ions are bonded to borohydride
ions (BH4). The commercially important ionic borohydrides are lithium borohydride,
sodium borohydride, and aluminum borohydride, whose chemical formulas are LiBl-Li,
NaBH4, and Al(B~ h, respectively. The ionic borohydrides are produced by relatively
complex chemical reactions.

9.5-C IONIC ALUMINUM HYDRIDES
Ionic alu~inu?1 hydrides are ionic hydrides in which metallic ions are bonded to ahuni·
num hydnde ions (A1H4 ). Two commercially import t · · 1 • h drides are
1. h’ 1 · h d ‘d . an tome a ummum y it mm a ummum y n e and sodium aluminum h d ‘d h h . 1 f ulas are . . Y n e, w ose c emica orm .
L1Al:I4 and NaAlH4, respe~tlvely. They are produced by reacting the relevant ionic
hydnde and anhydrous aluminum chloride (Section 9.S-A).

328 Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

,NATER REACTIVITY OF THE IONIC HYDRIDES
9,S·D h the ionic hydrides are relatively stable compounds they possess several com-
I houg f Of . I · ‘ At hazardous eatures. specia interest here is the fact that they react with water to

f!l00 flammable hydrogen.
oduce h . . h . d . pr ‘[o prevent t e1~ contact wit atmosphenc moisture, all ionic hydrides are store . m

. hrlY sealed containers. When enc?untered commercially, they are often covered with
ng I um oil. The presence of the 011 lends an element of safety when handling and stor-
etrO e h d h . P them- Howeve~, t _ese compoun s_ are also encountered as ethereal solutions; t _at 1s,

ing are dissolved m diethyl ether, a highly flammable liquid. The combination of diethyl
and an io~ic hydri~e po~es the risk of fire and explosion. . . .

‘[he following equations illustrate the water reactivity of several representative 1omc
hydrides:

LiH(s) + H20 (/) – LiOH(aq) + H2(g) Lithium hydride Water Lithium hydroxide Hydrogen
3NaBH4(s) + 6H20(I) – 3NaB02(aq) + l 2H2(g) Sodium borohydride Water Sodium borate Hydrogen
LiAIHi s) + 4H20(l) – Al(OH)3(s) + LiOH(aq) + 4H2(g) Lithium aluminum hydride Water Alumi num hydroxide Lithium hydroxide Hydrogen

Al(BH4)3(s) + 12H20( I) – Al(OH)3(s) + 3H3B03(aq) + 12H2(g) Aluminum borohydride Water Aluminum hydroxide Boric acid Hydrogen
As these ionic hydrides react with water, the evolved hydrogen absorbs the heat of reaction
and spontaneously bursts into flame.

Because the ionic hydrides are water-reactive substances, precautions should be exer-
cised to avoid exposing them to humid air or other potential sources of water. Experts
recommend that firefighters use water as a fire extinguisher only when they encounter
small spills of these substances.

9.5-E TRANSPORTING IONIC HYDRIDES
When shippers offer an ionic hydride for transportation, DOT requires them to provide the
appropriate shipping description on the accompanying shipping paper. Table 9.7 provides

TABLE 9.7 Shipping Descriptions of Some Representative Ionic Hydrides

IONIC HYDRIDE SHIPPING DESCRIPTION
Aluminum borohydride UN2870, Aluminum borohydride, 4.2, (4.3), PG I (Dangerous When Wet)

or
UN2870, Aluminum borohydride in devices, 4.2, (4.3), PG I (Dangerous
When Wet)

Calcium hydride UN1404, Calcium hydride, 4.3, PG I (Dangerous When Wet)
Lithium aluminum hydride UN1410, Lithium aluminum hydride, 4.3, PG I (Dangerous When Wet)
Lithium aluminum hydride
dissolved in ether

UN1411, Lithium aluminum hydride, ethereal, 4.3, (3), PG I (Dangerous
When Wet)

Lithium borohydride UN1413, Lithium borohydride, 4.3, PG I (Dangerous When Wet)
Lithium hydride UN1414, Lithium hydride, 4.3, PG I (Dangerous When Wet)
Sodium aluminum hydride UN2835, Sodium aluminum hydride, 4.3, PG II (Dangerous When Wet)
Sodium borohydride UN1426, Sodium borohydride, 4.3, PG I (Dangerous When Wet)
Sod ium hydride UN1427, Sodium h dride, 4.3, PG I (Dan erous When Wet y g

Sodium borohydride

Lithium aluminum
hydride

Chapter 9 Chemistry of Some Wate r- and Air-Reactive Substances 329

metallic phosphide
• An inorganic
compound composed
of metallic and
phosphide ions

Calcium
phosphide

some representative examples. When the shipping description is not listed at 49 C
§ 172.101, DOT requires them to identify the commodity generically and include th •P.R.
of the specific compound parenthetically. DOT also requires shippers and carriers t: nallle
ply with all applicable labeling, marking, and placarding requirements. coll).

9.6 METALLIC PHOSPHIDES
Metallic phosphides are produced by combination reactions in which a given metal u .
with elemental phosphorus. Calcium phosphide, for example, is formed by heatingnitels
. d h h ca. c1um an p osp orus.

Calcium Phosphorus Calcium phosphide

These compounds once were popular fumigants used on grain and other postharve
crops, but in the United States, their use is not nearly as po~ular ?ow as it was in the pas:’.

The metallic phosphides function as fumigants by reacting with atmospheric moisture
to produce the toxic gas phosphine.

Ca3P2(s) + 6H20(l) 3Ca(OH)2(s) + 2PH3(g)
Calcium phosphide Water Calcium hydroxide

Phosphine

When calcium phosphide is applied within an enclosure used for the storage of crops, it~
the phosphine produced by hydrolysis that actually kills mice and other unwanted pests.

9.6-A TRANSPORTING METALLIC PHOSPHIDES
When shippers offer a metallic phosphide for transportation, DOT requires them to iden-
tify the appropriate material on the accompanying shipping paper. Some examples of the
shipping descriptions for several representative metallic phosphides are listed in Table 9.8.
DOT also requires shippers and carriers to comply with all applicable labeling, marking, ‘
and placarding requirements.

SOLVED EXERCISE 9.3
What is the most likely reason that DOT requires shippers to affix DANGEROUS WHEN WET and POISON labels to
packages of stannic phosphide?
Solution: DOT assigns two hazard codes, 4.3 and 6.1, to stannic phosphide because the properties of this sub-
stance comply with the defining criteria for both a dangerous-when-wet substance and a poisonous material (Sec·
tion 10.1-C). Stannic phosphide is a solid compound that reacts with water to produce phosphine, a flammable and
toxic gas.

Stannic phosphide Water Stannic hydroxide Phosphine

When shippers affix DANGEROUS WHEN WET and POISON labels to packages of stannic phosphide, these hazard
warning labels quickly inform emergency responders that the substance is simultaneously water-reactive and toxic.

,…,…~ __ ,,,….,,,._,___…,….–!’!l”.”!””~ …….. ………. ~~~_,_/

9.6-B PHOSPHINE
As noted previously, phosphine is generated when metallic phosphides react with water.
This substance possesses the following hazardous features:

Phosphine is a poisonous gas. Toxicity is its primary haz:,ird. The gas may be
detected by its exceptionally offensive odor, which has been described as a mixture of
garlic and rotten fish. The odor threshold for phosphine is only 0.15 part per million,

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

rASLE 9.8
Shippi~g Descriptions of Some Representative
Metallic Phosphides

MffA
LLIC PHOSPHIDE SHIPPING DESCRIPTION
• urn phosphide UN1397, Aluminum phosphide, 4.3, (6.1), PG I (Dangerous

,Alurnin When Wet) (Poison) —.-:—.–:-:–:–t–_:_:_::..::…::._..:.:=’.:!._ _ _______ _
. urn phosphide (pesticides) UN3048, Aluminum phosphide pesticides, 6.1, PG I (Poison) ,Alulllln~.:._s~ ——+ – :….::._.:::…:…=:==.:.:.’….!:’.’..~~~~~~~’..’….:…::…:….’.:…::=-..::.-

calciUrTl phosphide UN1360, Calcium phosphide, 4.3, (6.1), PG I (Dangerous When
Wet) (Poison)

Magnesium phosphide UN2011, Magnesium phosphide, 4.3, (6.1), PG I (Dangerous
When Wet) (Poison)

potassium phosphide

sodiurn phosphide

UN2012, Potassium phosphide, 4.3, (6.1 ), PG I (Dangerous
When Wet) (Poison)
UN1432, Sodium phosphide, 4.3, (6.1), PG I (Dangerous When
Wet) (Poison)

When inhaled, it primarily attacks the cardiovascular and respiratory systems, causing
pulmonary edema (Section 7.3-B) and massive destruction of the lung tissues. Long-term
exposure to lesser concentrations causes the bones to soften. Exposure to a concentration
of 50 parts per million is immediately dangerous to an individual’s life and health.

I Phosphine is also a spontaneously flammable gas. Flammability is considered its
secondary risk. Its autoignition temperature is only 100°F (37.8°C), a value readily at-
rained in most environments. Phosphine burns in air to produce a dense white cloud of
retraphosphorus decoxide and water vapor.

Phosphine Oxygen Tetraphosphorus decoxide Water

We examine the methods recommended for extinguishing fires involving gases that
are simultaneously flammable and poisonous in Chapter 10.

9.6-C WORKPLACE REGULATIONS INVOLVING PHOSPHINE
When phosphine is present in the workplace, OSHA requires employers to limit employee
exposure to a concentration of 0.3 part per million, averaged over the 8-hour workday.

9.6-D TRANSPORTING PHOSPHINE
When shippers offer phosphine for transportation, DOT requires them to identify the gas
on the accompanying shipping paper as follows:

UN2199, Phosphine, 2.3, (2.1) (Poison – Inhalation Hazard, Zone A)

DOT also requires shippers and carriers to comply with all applicable labeling, marking,
and placarding requirements.

9.7 METALLIC CARBIDES
Metals bond with carbon to form compounds having either ionic or covalent units. Our
concern here is solely with the compounds composed of metallic ions and carbon ions
that exist as ct or c4-. They are called metallic carbides. There are only two commer-
cially important metallic carbides: aluminum carbide and calcium carbide. Both are water-
reactive substances. ·

Phosphine

metallic carbide An
inorganic compound
composed of metallic
and carbide ions

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 331

I
I

Aluminum
carbide

Calcium carbide

Anhydrous
aluminum chloride

TABLE 9.9 Shipping Descriptions of Metallic Carbides

METALLIC CARBIDE SHIPPING DESCRIPTION

Aluminum carbide
Calcium carbide

UN1394, Aluminum carbide, 4.3, PG 11 (Dangerous When Wet)
UN1402, Calcium carbide, 4.3, PG I (Dangerous When Wet)

9. 7-A ALUMINUM CARBIDE
Aluminum carbide is prepared by heating aluminum oxide wit~ coke in ~n electric fur.
nace. It is used as a catalyst by the chemical industry._When alummum carbide reactswitn
water, flammable methane is produced as a hydrolysis product.

AJ
4
C

3
(s) + J 2Hz0(/) –+ 4Al(OH)3(s) + 3CH4(g)

Aluminum carbide Water Aluminum hydroxide Methane

Aluminum carbide that has been exposed to humid air poses a flammable and explosive hazard.

9.7-B CALCIUM CARBIDE
Calcium carbide is manufactured by heating a mixture of coke and lime at an elevated
temperature in an electric furnace.

CaO(s) + 3C(s) – CaC2(s) + CO(g) [t > 3600°F ( l 982°C)]
Calcium oxide Carbon Calcium carbide Carbon monoxide

The production process is very energy-intensive.
Calcium carbide formerly was used as a raw material for the production of industrial-

grade acetylene.

CaC2(s) + 2Hz0({) – Ca(OH)z(s) + C2H2(g)
Calcium carbide Water Calcium hydroxide Acetylene

Today, this method of producing and manufacturing acetylene is used to a very limited
extent because it produces a huge amount of calcium hydroxide slag. Although some of
this slag is incorporated into cement, acetylene manufacturers often choose to avoid deal·
ing with the negative environmental impact altogether.

Because of its water-reactive nature, calcium carbide that has been exposed to humid
air poses a flammable and explosive hazard. For this reason, it must be stored and ban·
died in a dry environment that is free of ignition sources.

9.7-C TRANSPORTING METALLIC CARBIDES
When shippers offer aluminum carbide or calcium carbide for transportation, DOT
requires them to identify it as shown in Table 9.9 on the accompanying shipping papet
DOT also requires shippers and carriers to comply with all applicable labeling, markmg,
and placarding requirements.

9.8 WATER-REACTIVE SUBSTANCES THAT
PRODUCE HYDROGEN CHLORIDE

Certain substances react with water to produce hydrogen chloride vapor or hydrochloric
acid as products of their hydrolysis. When they are encountered these substances rou·
tinely have the suffocating, pungent odor of hydrogen chloride ~hich fumes in air aflcl
limits visibility. As first noted in Chapter 8, hydrogen chloride ‘is a toxic, irritating gas,

332 Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

d hydr
ochloric acid is a corrosive liqui·d. I h” · h h d 1 · d · n t 1s section, t e y ro ys1s pro uct 1s

d~noted solely as hydrogen chloride vapor.

s-A ALUMINUM CHLORIDE, ANHYDROUS
9′ 1 . hl “d · Anhydrous a umu~um _c on e is a wh!te-to-yellow solid whose chemical formula is
AICl3• In the chemical

1_ndustry su~stantial quantities are used as catalysts and as a raw
cerial for the production of aluminum alkyl compounds and lithium aluminum hydride.

(Ila d d . · . also use to pro uce ant1persp1rants.
JtlS dr 1 . hl “d AnhY ous a Uffilnum c on e reacts violently with water to produce hydrogen chloride.

2AICl3(s) + 3H20(l) – Ai 20 3(s) + 6HCl(g)
Aluminum chloride Water Aluminum oxide Hydrogen chloride

for this reason, the manufacturers and distributors of this substance caution potential
users that it irritates the skin, eyes, and respiratory tract.

g,S-8 PHOSPHORUS OXYCHLORIDE
Phosphorus oxychloride, also called phosphory/ chloride, is a colorless, fuming liquid
whose chemical formula is POCl3. It is used primarily by the chemical industry as a chlo-
rinating agent.

Phosphorus oxychloride reacts violently with water to produce hydrogen chloride.

POCl3(l) + 3H20(l) – H 3P04(aq) + 3HCl(g)
Phosphorus oxychloride Water Phosphoric acid Hydrogen chloride

9.8-C PHOSPHORUS PENTACHLORIDE
This substance is a yellow-to-green solid whose chemical formula is PCl5. It is primarily
used as a chlorinating and dehydrating agent by the chemical industry.

Phosphorus pentachloride is decomposed by water in a multistep process, summa-
rized in the following equation:

PC15(s) + 4H20(l) H3P04(aq) + 5HCl(g)
Phosphorus pentachloride Water Phosphoric acid Hydrogen chloride

9.8-D PHOSPHORUS TRICHLORIDE
This substance is a colorless, fuming liquid whose chemical formula is PCl3. It is used in
the chemical industry as a chlorinating agent and catalyst. Phosphorus trichloride is used,
for example, as a raw material for producing acetyl chloride (Section 9.9-C).

Phosphorus trichloride reacts with water to form phosphorous acid and hydrogen
chloride.

Phosphorus trichloride Water Phosphorous acid Hydrogen chloride

9.8-E SILICON TETRACHLORIDE
Silicon tetrachloride is a colorless, fuming liquid whose chemical formula is SiC14• It is
used as a raw material to manufacture liquid or semisolid silicon-containing polymers
known as silicones, substances widely used in electrical insulation. Silicon tetrachloride is
also used in the semiconductor manufacturing industry.

Silicon tetrachloride reacts vigorously with water to form silicic acid and hydrogen
chloride.

Silicon tetrachloride Water Silicic acid Hydrogen chloride

Phosphorus
oxychloride

Phosphorus
pentachloride

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 333

I ‘

Ii

Phosphorus
trichloride

Silicon
tetrachloride

silane An organic
compound whose
molecules are
composed of silicon
and hydrogen atoms

chlorosilane A
chlorinated derivative
of silane (SiH4)

9.8-F SULFURYL CHLORIDE
Sulfuryl chloride also called su/lony/ chloride, is a colorless liquid whose chemic 1 ‘ ” · · h h · 1 · d a fo mula is SO?Cl2. Sulfuryl chloride is used mamly mt e c erruca m UStry as a chlorin . r– a~
and dehydrating agent. . . g

Sulfuryl chloride reacts slowly with water to form sulfuric acid and hyd
chloride. rogen

S0 2Ci 2(l) + 2Hz0(/) —? H2S04Caq) + 2HCl(g)
Sulfuryl chloride Water Sulfu ric acid Hydrogen chloride

9.8-G THIONYL CHLORIDE
Thionyl chloride is a red-to-yellow liquid whose chemical formula is SOCl2, Thionyl chlo.
ride is used mainly within the chemical industry.

Thionyl chloride reacts vigorously with water to form sulfurous acid and hydrogen
chloride.

SOCI2(l) + 2H20(l) —? H2S03(aq) + 2HCl(g)
Thionyl chloride Water Sulfurous acid Hydrogen chloride

9.8-H TIN(IV) CHLORIDE, ANHYDROUS
Tin(IV) chloride, also known as stannic tetrachloride, is a colorless, fuming liquid whose
chemical formula is SnC14. It is used to manufacture blueprint and similarly sensitized
types of pa per.

Anhydrous tin(IV) chloride reacts slowly with water to form tin(IV) oxide and hydro-
gen chloride.

SnCl4(/) + 2H20(l) —? Sn02(s) + 4HCl(g)
Tin(TV) chloride Water Tin(IV) oxide Hydrogen chloride

9.8-1 TITANIUM(IV) CHLORIDE, ANHYDROUS
Titanium(IV) chloride, also called titanium tetrachloride, is a colorless, volatile liquid
whose chemical formula is TiCl4. Titanium(IV) chloride is the intermediate compound
produced during the production of metallic titanium and the white paint pigment tita-
nium dioxide. The mixture of titanium(IV) chloride and an aluminum alkyl compound is
an important polymerization catalyst (Section 9.4).

Titanium(IV) chloride reacts slowly with water to produce titanium(IV) dioxide and
hydrogen chloride.

TiCl4(/) + 2H20(/) Ti02(s) + 4HCl (g)
Titanium(IV) chloride Water Titanium(IV) oxide Hydrogen chloride

9.8-J CHLOROSILANES
The hydrides of silicon are called silanes. They consist of a class of compounds having the
chemical formula SinH2n+2, where n is a nonzero integer. The simplest silane, itself called
si/ane, is a substance having the formula Si~. When one or more of the hydrogen atoms
in a silane molecule is replaced with a chlorine atom, the resulting substances are called
chlorosilanes. All chlorosilanes are water-reactive substances.

The chlorosilanes are used predominantly in the polymer industry. For example, tri·
chlorosilane is used to manufacture the polysilicon employed for the production of solar
cells and solar wafers. Some of its physical properties are noted in Table 9.10. It is a
water-reactive, flammable, and corrosive liquid having the chemical formula SiHCJ3.

334 O.apter 9 Chemist,y of Some Water- and Air-Reactive Substances ……oil

1ASLE 9.10 Physical Properties of Some Chlorosilanes

METHYLDICHLOROSILANE METHYL

TRICHLOROSILANE

r,,elting point -135°F ( 93°C) -130°F (-90°cJ

soiling point 106°F (41 °C) 149°F (66.4°C)
·fc gravity at 68°F (20 °C) 1.1 1.27 5peCI I .

density (air= 1) 3.97 5.2 vapor
pressure at 68°F (20°C) 321 mmHg 134 mmHg vapor

Flashpoint -18°F (-28°c) 14°F(-10°C)

Autoign ition point 471 °F (244°C) 759°F (404°C)

LOW
er flammable lim it 3.4% by volume 3.4% by volume
r flammable limit 55% by volume >55% b volume y

Trichlorosilane reacts violently with water, producing choking vapors of hydrogen chlo-
ride and crihydroxysilane.

H- SiCl3(/) + 3H20(I) – H- Si(OH)3(s) + 3HCl(g)
Trichlorosilane Water Trihydroxysilane Hydrogen chloride

Other chlorosilanes, including methyldichlorosilane and methyltrichlorosilane, possess
similar hazardous properties. Their physical properties are included in Table 9.10.

9,8-K TRANSPORTING SUBSTANCES THAT REACT WITH WATER
TO PRODUCE HYDROGEN CHLORIDE VAPOR

When shippers transport any substance noted in this section, DOT requires them to
provide the relevant shipping description shown in Table 9.11 on the accompanying
shipping paper. DOT also requires shippers and carriers to comply with all applicable
labeling, marking, and placarding requirements.

TRICHLOROSILANE

-196°F (-127°C)

89°F (32°C)

1 .33

4.7

500 mm Hg

7°F (-14°C)

219 °F (104°C)

1 .2% by volume

90.5% by volume

Sulfuryl
chloride

TABLE 9.11
I

Shipping Descriptions of Substances That Produce Hydrogen Chloride
Upon Reacting with Water

WATER-REACTIVE SUBSTANCE SHIPPING DESCRIPTION

Aluminum chloride, anhydrous UN1726, Aluminum chloride, anhydrous, 8, PG II

Methyldichlorosilane UN1242, Methyldichlorosilane, 4.3, (8), (3), PG I (Dangerous When Wet)

Methyltrichlorosilane UN 1250, Methyltrichlorosilane, 3, (8), PG I

Phosphorus oxychloride UN1810, Phosphorus oxychloride, 6. 1, (8), PG II (Poison – Inhalation Hazard, Zone B)

Phosphorus pentachloride UN1806, Phosphorus pentachloride, 8, PG II

Phosphorus trichloride UN1809, Phosphorus trichloride, 6.1, (8), PG I (Poison – Inhalation Hazard, Zone B)

Silicon tetrachloride UN1818, Silicon tetrachloride, 8, PG II

Stannic chloride, anhydrous UN 1827, Stannic chloride, anhydrous, 8, PG II

Sulfuryl chloride UN1834, Sulfuryl chloride, 6.1, (8), PG I (Poison – Inhalation Hazard, Zone A)

Thionyl chloride UN1836, Thionyl chloride, 8, PG I

Titanium tetrachloride, anhydrous UN1838, Titanium tetrachloride, 6.1, (8), PG II (Poison – Inhalation Hazard, Zone B)

Trichlorosilane UN1295, Trichlorosilane, 4.3, (8), (3), PG I (Dan erous When Wet g

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 335

SOLVED EXERCISE 9.4

Thionyl
chloride

Anhydrous
Tin(IV) chloride

Why should emergency responders use protective gear including self-contained breathing apparatu
tigating a transportation mishap involving a massive spill of liquid methyldichlorosilane?

5
When inves.

Solution: k, indicated by the shipping description in Ta?le 9.11.’ methyldichlorosilane is a “.”ater-reactive, fl
and corrosive liquid. When it reacts with water, methyld1chloros1\ane forms hydrogen chloride vapor. Tab\ arnrnable
that the inhalation of this vapor causes exposed individuals to experience a variety of adverse health effe~·

9
sh~

hydrogen chloride poses a health hazard by inhalation, the use of self-contained breathing apparatus . · Becaose
when emergency responders are investigating a transportation mishap involving methyldichlorosilane. Js essential

DOT requires carriers to display DANGEROUS WHEN WET placards on the hulk
aging or transport vehicle used to transport trichlorosilane, and when transporting an :ck.
exceeding 1001 pounds (454 kg), to display FLAMMABLE and CORROSIVE placards as~:
9.9 WATER-REACTIVE COMPOUNDS THAT

PRODUCE ACETIC ACID VAPOR
When acetic acid is formed as a product of a chemical reaction, its highly irritating and
pungent odor is immediately evident. This can pose serious consequences, as the inhalatio
of acetic acid vapor is suffocating, and exposure to the eyes an~ nose is severely irritatint

We briefly note here two organic compounds that react with water to produce acetic
acid vapor: acetic anhydride and acetyl chloride. Some physical properties of these com-
pounds are provided in Table 9.12.

Acetic anhydride causes severe burns on contact with the skin or eyes. Inhalation of
its vapor is suffocating and causes irritation of the respiratory tract. Before the advent of
the GHS, chemical manufacturers often marked acetic anhydride containers as follows to
warn users of these potential hazards:

DANGER: CORROSIVE
CAUSES BURNS TO ANY AREA OF CONTACT

FLAMMABLE LIQUID AND VAPOR WATER REACTIVE
HARMFUL IF SWALLOWED OR INHALED

VAPOR CAUSES RESPIRATORY TRACT
IRRITATION AND SEVERE EYE IRRITATION

9.9-A ACETIC ANHYDRIDE
Acetic anhydride is a colorless, fuming liquid whose condensed chemical formula is (CH3CO)iO.
Acetic anhydride is used principally by the chemical, pharmaceutical, and polymer industries
for the manufacture of aspirin, cellulose acetate (Section 14.5-A), and related products.

When acetic anhydride combines with water, the sole product produced is acetic acid.

0
II

CH3 – C
\
O(l) + H20(l)
I

CH3-C
i
0

Acetic anhydride Water

0
//

2CH3-C(g)
\
OH

Acetic acid

336 Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

rASLE 9.12
Physical Propert· f . . 1es o Two Water-Reactive Organic
Compounds

ACETIC ANHYDRIDE ACETYL CHLORIDE

Melting point -99°F (-73°C) -170°F (-112°C)

soiling point 284°F c14o•ci 124°F cs1°ci

•fie gravity at 68°F (20°C) 1.08 1.10 specI
vapor density (air= 1) 3.52 2.7

vapor pressure at 68°F (20°C) 4mmHg 249 mmHg

Flashpoint 130°F (54 °C) 40°F (4.44°C)

Autoignition point 734°F (390°c) 734°F (390°c)

Lower flammable limit 2.7% by volume 7.3% by volume

u PP er flammable limit 10.3% b y volume 19% b volume y

g,9-B WORKPLACE REGULATIONS INVOLVING
ACETIC ANHYDRIDE

When acetic anhydride is used in the workplace, OSHA requires employers to limit employee
exposure to a concentration of 5 parts per million, averaged over the 8-hour workday.

9.9-C ACETVL CHLORIDE p
Acetyl chloride is a colorless, fuming liquid with the chemical formula CH3-C . Acetyl

\
Cl

chloride is used principally in the chemical industry. It is produced by various means, one
of which involves the reaction between phosphorus trichloride and acetic acid.

0 0
II II

PCl3(/) + 3CH3 – C(/) —–? 3CH3 – C(/) + H3PO3(/)
\ \
OH Cl

Phosphorus trichloride Acetic acid Acetyl chloride Phosphorous acid

On contact with water, acetyl chloride reacts violently, producing acetic acid and hydro-
chloric acid vapor. This vapor poses the risk of inhalation toxicity.

0 0
II II

CH3 – C(/) + H2O(/) —–? CH3 -C(g) + HCl(g)
\ \
Cl OH

Acetyl chloride Water Acetic acid
Hydrogen chloride

Table 9.12 reveals that acetyl chloride has a relatively low flashpoint. Consequently, acetyl
chloride also poses a dangerous risk of fire and explosion.

9.9-D TRANSPORTING ACETIC ANHYDRIDE
AND ACETYL CHLORIDE

When shippers offer either acetic anhydride or acetyl chloride for transportation, DOT
requires them to identify it as shown in Table 9.13 on the accompanying shipping paper.
DOT also requires shippers and carriers to comply with all applicable labeling, marking,
and placarding requirements.

Anhydrous
titanium(IV) chloride

Methyldichloro-
silane

Methyltrichloro-
silane

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 337

338

Trichloro-
silane

Acetic
anhydride

TABLE 9.13
Shipping Descriptions of Organic Compounds That
Produce Acetic Acid Vapor Upon Reacting With Water

WATER-REACTIVE COMPOUND SHIPPING DESCRIPTION

Acetic anhydride UN 1715, Acetic anhydride, 8, (3), PG II

Acetyl chloride
UN1717, Acetyl chloride, 3, (8), PG 11

9.10 RESPONDING TO INCIDENTS INVOLVING
THE RELEASE OF A MATERIAL IN HAZARD
CLASSES 4.1, 4.2, AND 4.3

When a flammable solid, spontaneously combustible material, or water-reactive substance
is involved in a transportation mishap, first-on-the-scene responders may readily identify
it by noting the following, as relevant:

(a) A flammable solid
The number 4.1 as a component of a shipping description of a hazardous material
listed on a shipping paper
The words FLAMMABLE SOLID and the number 4 printed on white-and-red-
striped labels affixed to packaging
The words FLAMMABLE SOLID and the number 4 printed on white-and-red-
striped placards displayed on each side and each end of a transport vehicle contain-
ing 1001 pounds (454 kg) or more of a flammable solid

(h) A spontaneously combustible material
The number 4.2 as a component of a shipping description of a hazardous material
listed on a shipping paper
The words SPONTANEOUSLY COMBUSTIBLE and the number 4 printed on
white-and-red labels affixed to packaging
The words SPONTANEOUSLY COMBUSTIBLE and the number 4 printed on
white-and-red placards displayed on each side and each end of a transport vehicle
containing 1001 pounds (454 kg) or more of a spontaneously combustible material

(c) A water-reactive material
The number 4.3 as a component of a shipping description of a hazardous material
listed on a shipping paper
The words DANGEROUS WHEN WET and the number 4 printed on blue labels
affixed to their packages
The words DANGEROUS WHEN WET and the number 4 printed on blue plac·
ards displayed on each side and each end of the transport vehicle

Although it is always desirable to know the chemical identity of a hazardous material
involved in any transportation mishap, this statement has special meaning to the firSC
responders a~riving at scene involving a substance that could spontaneously burst int:
flame or readily react with water. These responders are confronted with a unique challeng ‘
because the use of most common e~nguishers would exacerbate the ongoing emergencY:
. The ~mergenc~ Response G~tdebook provides emergency responders with special
mformauon regar_dmg th_e followmg hazardous materials: gases and volatile liquids that
pose a hazard by mhalat10n toxicity· chemical warfar t d t ‘ve rnare-. 1 h d • ‘ e agen s; an water-reac 1
na s t at pro uce toxic gases upon contact with t Th ERG ‘d ‘f’ h se haz·

d
· 1 b h • . . . wa er. e 1 entl 1es t e h

ar ous matena s y t eir DOT identification nu b d b h ‘ . h • in bot m ers an y green 1ghhg ung
Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

….illlll

UoW· and blue-bordered sections Th E
1be ye nt the following actio . · e RG further directs emergency responders ·Jllplerne ns.
[O l • .

When there is no fire, go directly t h • b d name of th h d O t e gr~en-bordered pages, locate the identifica-
cioll nu_rn er ~n di’stanc e azar ous material, and identify the initial isolation and

cove-action es.
prote “”hen a fire is involved also co 1 h . . • w . f . h ‘ nsu t t e orange guide and, 1f applicable, apply the

Uation in ormation s own under PUBLIC SAFETY evac .
oOT provides two entries in the green-bordered pages of the ERG one for land-based

spills and ~he 0ther for water-based ~pills. ~hen a -~ater-reactive mat:rial is not a hazard-
ous rnatenal that poses a hazard by inhalation toxicity, and when it is not spilled in water,
ernergency respo~ders should consult the safety distances in the orange-bordered pages.

Because s_pecial pro~edu~es are required when responding to fires involving the haz-
ardous rnatenals noted m this chapter, we briefly note the recommended practices for the
following groups of substances.

g,10-A ALKALI METALS
Fires involving the alk_ali metals are extremely difficult to extinguish. When first-on-the-
scene responders consider a response action involving an alkali metal fire, it is appropri-
ate to recall that these elements react with two common fire extinguishers, water and
carbon dioxide. Alkali metal fires cannot be extinguished with water, because the alkali
metals displace flammable hydrogen from water. Furthermore, alkali metal fires cannot
be extinguished with carbon dioxide, because the alkali metal reacts with it to produce
carbon particulates.

4Na(s) + C02(g) – 2Na20(s) + C(s)
Sodium Carbon dioxide Sodium oxide Carbon

Because this reaction is exothermic, the underlying metal usually erupts into flame as the
carbon dioxide dissipates.

The use of a dry-chemical or dry-powder fire extinguisher frequently is recommended
for extinguishing or controlling the spread of alkali metal fires. Nonetheless, caution
needs to be exercised when using graphite-based dry powder to extinguish an alkali metal
fire. Graphite effectively extinguishes the fire by a smothering action, thereby limiting the
amount of atmospheric oxygen and moisture available to the metal. At the high tempera-
tures accompanying alkali metal fires, however, the graphite may react with the metal to
produce metallic carbides. As previously noted in Section 9.7, these compounds are water-
reactive substances. Even the moisture in the air could cause the alkali metal to reignite.

When combating fires involving nonbulk quantities of lithium, two fire extinguishing
agents are uniquely recommended for use: lithium chloride, a dry-chemical fire extinguisher;
and LITH-X, the graphite-based dry-powder extinguisher illustrated in Figure 9.6. Both
effectively function by their smothering action. The use of LITH-X is also recommended for
extinguishing magnesium, sodium, potassium, and zirconium fires.

When primary lithium batteries are involved in a fire, large volumes of water can be
used to consume the lithium, but experts consider the use of LITH-X to be preferable.

9.10-B COMBUSTIBLE METALS
Firefighters frequently are warned against using water on combustible metal fires . Not-
withstanding this generally sound advice, water effectively extinguishes combustible metal
fires when the following two conditions are met:
1 The water is discharged in a volume that totally deluges the fire scene and cools the metal.
1 The water is discharged rapidly soon after the metal first ignites.

Acetyl
chloride

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 339

FIGURE 9.6 LITH-X dry
powder, a graphite-based
fire extinguisher. Although
it was initially developed
to extinguish lithium fires
LITH-X also extinguishes ‘
magnesium, sodium,
potassium, and zirconium
fires. (Courtesy of Tyco Fire
Protection Products, Lansdale,
Pennsylvania.)

Firefighters must consider not only whether enough water is available at the fire scene but
also whether an appropriate means is available to rapidly apply it to the fire.

When a deluging volume of water is unavailable for extinguishing a combustible
metal fire, experts recommend the use of dry sand, earth, dry-chemical extinguishers, or
dry powders. The application of a special extinguishing agent is recommended for use on
specific combustible metal fires. For example, the use of MET-L-X is recommended for
extinguishing fires involving nonbulk quantities of metallic magnesium, titanium, zirco·
nium, and aluminum.

The fire-extinguishing agent used in the MET-L-X extinguisher, shown in Figure 9.7,
is primarily sodium chloride containing a plastic additive. The metal fire causes the plastic
to melt, thereby forming a crust on the surface of the burning metal. This effectively pre·
vents contact between the burning metal and atmospheric oxygen. It is the displacement
of the oxygen that causes the fire to be smothered.

The application of carbon dioxide is not recommended for extinguishing combustible
metal fires, because these hot metals react with carbon dioxide. Magnesium, for example,
reacts with carbon dioxide to produce a sooty plume of carbon.

2Mg(s) + C02(g) – 2MgO(s) + C(s)
Magnesium Carbon dioxide Magnesium oxide Carbon

Because this reaction is exothermic, the use of carbon dioxide does not cool the burning
metal, and the magnesium fire is not extinguished.

340 Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

The environment of a class D fire can be extremely caustic because of the formation
of the corresponding metallic oxides, hydroxides, and carbonates. The particulates of
such compounds are constituents of the smoke accompanying alkali metal and combus-
tible metal fires. Their inhalation can cause adverse health effects ranging from minor
irritation and congestion of the nose, throat, and bronchi to severe lung injury. Because
combustible metal fires frequently burn with exceptionally brilliant flames, firefighters
should be aware that the evolved radiant energy could damage the retinas of their eyes.
They should also avoid breathing the smoke evolved during these fires, as it contains tiny
particulates of caustic metallic oxides. When inhaled, exposure to these particulates
causes considerable discomfort and localized injury to the respiratory tract and inflam-
mation of the eyes. 1

9.10-C ALUMINUM ALKYL COMPOUNDS AND METALLIC HYDRIDES,
PHOSPHIDES, AND CARBIDES

When first-on-the-scene responders encounter the release of an aluminum alkyl compound
or a metallic hydride, phosphide, or carbide from its packaging, experts recommend the
use of vermiculite, dry sand, or dry powder pressurized with nitrogen to extinguish fires.

1NFPA 484, Standard for Combustible Metals (Quincy, Massachusetts: National Fire Protection Association, 2012).

FIGURE 9.7 MET-L-X, a
sodium chloride-based
fire extinguisher intended
for use on NFPA class D
fires, especially magne-
sium fires. (Courtesy of
7yco Fire Protection Products,
Lansdale, Pennsylvania.)

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 341

FIGURE 9.8 This portion
of the label affixed to
containers of sodium
hydride communicates
hazard information that
includes caution against
exposing the contents to
water.

SODIUM HYDRIDE

UN1427, Sodium hydride

DANGER
In contact with water, releases flammable gases that may ignite
spontaneously. Causes mild skin irritation. Causes serious
eye irritation.

Keep away from possible contact with water because of violent
reaction and possible flash fire. Handle under inert gas.
Protect from moisture.

In case of fire: Use dry sand, dry chemical or alcohol-resistant foam
for extinction. Store contents under inert gas.

FIRST-AID INSTRUCTIONS:

IF ON SKIN: Remove immediately all contaminated clothing.
Rinse with water/shower.

IF IN EVES: Rinse cautiously with water for several minutes.
Remove contact lenses, if present, and easy to do. Continue rinsing.
Immediately call POISON CENTER or doctor.

Read Safety Data Sheet before use.

My Company
My Street

My Town, My State 00000
Telephone (000) 000-0000

The container label in Figure 9.8 shows that caution should be exercised to avoid
exposing sodium hydride to humid air or other potential sources of water. Experts recom·
mend the use of water as a fire extinguisher only when they encounter very small spills of
these substances.

9.10-D WATER-REACTIVE SUBSTANCES THAT GENERATE
HYDROGEN CHLORIDE

When responding to a transportation mishap involving the release of any substance
listed in Table 9.13, firefighters should use water only sparingly and cautiously. Du~t
the corrosiveness of these products and their potential to form hydrogen chlo~i
responders must wear fully-encapsulated protective clothing and use self-containe
breathing apparatus.

9.10-E ACETIC ANHYDRIDE AND ACETYL CHLORIDE
To extinguish fires involving acetic anhydride or acetyl chloride, experts recommend ~he
of carbon dioxide or dry chemical. When emergency responders are called to a scene invo vd
ing a release of acetic anhydride or acetyl chloride, they should wear fully-encapsulate f
protective clothing, use self-contained breathing apparatus, and totally avoid rhe use

0

water as a fire extinguisher.

342 Chapter 9 Chemistry of Some Water- and Air-Reactive Substances