Categories for Chemistry

Sucralose Essay

Sucralose Essay

Sucralose (1,6-dichloro-1,6-dideoxy-b-D-fructo-furanosyl 4-chloro-4-deoxy-a-D-galactopyranoside), sold under the trade name Splenda (R), is usually categorized as non-nutritive sweetener or flavor enhancer. The molecular formula is C12H19Cl3O8 (1). It exists at room temperature as a white to off-white, crystalline powder, which is freely soluble in water, in methanol, and in alcohol, and slightly soluble in ethyl acetate (1). Sucralose has molecular weight of 397. 64 (2). As a sweetener, it has 400 to 800 times that of sucrose (2).

Its melting point has been recorded as 130 degrees Celsius, and the boiling point is between 614.

and 724. 4 degree Celsius under the condition of press 760 Torr (3). Sucralose is stable in solution at low pH, and also stable in solution at high temperatures as sucrose. Therefore, it can be stored for several years in liquids (3). The density of sucralose is about 1. 694 g/cm3 (3). The below chemical structure for sucralose was retrieved from the Dictionary of Food Compounds (2): Sucralose was first synthesized by Hough and co-workers at the Queen Elizabeth College at the University of London during the 1970s and was developed commercially as an intense sweetener by Tate & Lyle, LLC and McNeil Specialty Products Co (4).

Sucralose is made by the selective substitution of three hydroxyl groups of sucrose with three chlorine atoms, which was first approved as a food additive in Canada in 1992 and has subsequently been approved in over 80 countries as an intense sweetener (4). Sucralose can be slowly hydrolyses to the two monosaccharides 1,6-dicholorofructose (1,6-DCF) and 4-chlorogalactose (4-CG) under severe acidic conditions, so the formula cannot be found in natural waters (4). Sucralose is usually used in baked goods, sugars, alcoholic drinks, dairy products, cereals, fruit, beverages and nut products (3).

In general, sucralose may cause toxicity to aquatic organisms at concentrations ? 1123 mg/L (4). A range of long-term mammalian toxicity studies indicates that sucralose has no known specific mode of toxic action and causes no adverse effects on major physiological systems (4). Recent research concerns that the potential biological effects in non-target species living in areas receive discharges from anthropogenic activities due to the widespread usage and the high stability of sucralose.

The Predicted Environmental Concentration (PEC) for sucralose, based on measured data in surface water, was determined to be 10 ? g/L. During the process, data support that sucralose does not cause toxic effects. In conclusion, the resulting conservative PEC risk quotient is 0. 08, thus indicating low risk to aquatic organisms. Although available data suggest that sucralose is persistent in the aquatic environment, current knowledge also suggests that this intense sweetener should not be classified either as bioaccumulative or toxic using standardized and regulatory valid PBT criteria (4).

Sample Written Report Essay

Sample Written Report Essay


The periodic table is a table in which all of the known elements are listed. The table arranges the elements in order of increasing proton number to show the similarities of chemical elements. Therefore elements with structural similarities & atomic number are placed together. These elements can be placed into two different categories, metals & non-metals.

The early years of the 19th century witnessed a rapid development in chemistry. The art of distinguishing similarities and differences among atoms prompted scientists to devise a way of arranging the elements.

Relationships were discerned more readily among the compounds than among the elements; thus, the classification of elements lagged many years behind the classification of compounds.

Development of the Periodic Table

It was in 1817 when Johann Wolfgang Döbereiner showed that the atomic weight of strontium lies midway between those of calcium and barium. Some years later he showed that other such “triads” exist (chlorine, bromine, and iodine and lithium, sodium, and potassium).

Another way of classifying the elements was later proposed by John Alexander Reina Newlands in 1864. He proposed that elements be classified in the order of increasing atomic weights.

As a result of an extensive correlation of the properties and the atomic weights of the elements in 1869, Dmitri Inovich Mendeleev proposed the periodic law, which states that “the elements arranged according to the magnitude of atomic masses show a periodic change of properties.”

Mendeleev’s Version of Periodic Table

The rows 1 to 7 are called periods. The columns I A on the left to 0 on the right are known as groups. Elements with similar properties fall into vertical columns (groups) and horizontal rows (periods), which form the table. The columns in the table are called Groups. The elements in a group have the same number of electrons in their outer shell.

Arrangement of the Elements According To Groups

Group I A – The Alkali Metals

Group 1 elements are soft silvery metals. They react strongly with water. The further down the group you go, the more violent this reaction is. These alkali metals are usually stored under oil to protect them from moisture and oxygen. They all have one electron in their outer shells.

Group II A – The Alkaline Earth Metals

This group consists of all metals that occur naturally in compound form. They are obtained from mineral ores and form alkaline solutions. These are less reactive than alkali metals.

Group III A – The Aluminum Group

The elements in this group are fairly reactive. The group is composed of four metals and one metalloid which is boron.

Group IV A – The Carbon Group

This group is composed of elements having varied properties because their metallic property increases from top to bottom meaning the top line, which is carbon, is a nonmetal while silicon and germanium are metalloids, and tin and lead are metals.

Group V A – The Nitrogen Group

Like the elements in group IV A, this group also consists of metals, nonmetal and metalloids.

Group VI A – The Oxygen Group

This group is called the oxygen group since oxygen is the top line element. It is composed of three nonmetals, namely, oxygen, sulfur and selenium, one metalloid, (tellurium) and one metal (polonium)

Group VII A – The Halogens

This group is composed of entirely nonmetals. The term “halogens” comes from the Greek word hals which means salt and genes which means forming. Halogens group are called “salt formers”.

Group VIII A – The Noble Gases

This group is composed of stable gases otherwise known as the non-reactive or inert elements.
The Transition Elements
The elements in the middle of the table are called transition elements.
They are all metals and so they are also called transition metals.


A. Development of the Periodic Table

1. Johann Wolfgang Döbereiner classified elements in sets of three.

2. Dmitri Inovich Mendeleev devised the first periodic table, which he used to predict three new elements. He proposed the”periodic law” which states that when elements are arranged in order of increasing atomic number, their properties show periodic pattern.

B. The Periodic Table and the Elements

1. The periodic table is composed of 7 rows or periods and 18 major groups or columns.

2. The elements are given symbols devised by John Jacob Berzelius. An element is named after its discoverer, place of discovery, first letter of the name of the element, first and the second letter for those having the same first letter and some are after their Latin names. The elements are grouped into Group A and B Group by the INTERNATIONAL UNION OF PURE AND APPLIED CHEMISTRY (IUPAC).

3. Elements in the periodic table are also grouped according to metals, non-metals and metalloids. Metals are lustrous, malleable and ductile. They are good conductors of heat. Metals are found on the left side of the periodic table. Nonmetals have a diverse set of properties. They are found on the upper right side of the periodic table. Metalloids or semimetals possess the properties of both the metals and the non-metals.


The Periodic Table of Elements supports Chemistry, as it explains periodic law and the significance of the rows and columns of the periodic table, including how to relate the position of an element in the table to its atomic number and atomic mass. Students’ comprehension of the significance of the table will be reinforced as they learn how to use it to identify metals, semimetals, nonmetals and halogens, as well as the relative sizes of ions and atoms. The program also outlines the physical and chemical qualities of the members of each group of elements from the alkaline metals to the noble gases.

Titration Lab Essay

Titration Lab Essay

The equivalence point is characterized by a sharp change of pH which can be followed with a pHmeter. A graph of pH versus concentration will indicate the molar equivalence at the inflexion point of the curve. The point observed experimentally is never exactly the molar equivalence but a “best estimate” and is given the name “end point”. It is easier and cheaper to identify the end point with an indicator instead a pHmeter. Some chemicals such as phenolphthalein will change color when the pH changes sharply between two given values called the indicator’s range.

The range of phenolphthalein is 8. 3 to 10. 0. The shape of a pH curve varies widely with the type of reactants and needs to be taken into account when choosing an indicator. We will titrate a strong base (NaOH) of unknown concentration with a strong acid (HCl). The objective is to find the purity of NaOH pellets. The pellets are close to purity but not 100 % because NaOH is very hydrophilic and the pellets are likely to be slightly hydrated.

The procedure: The first part of the laboratory experiment will be the preparation of the reactants and the choice of an indicator.

You will need to prepare the analyte, a solution of NaOH, of a chosen concentration and volume and prepare a solution of HCl, the titrant, accordingly. Accordingly means that the end point should be reached after the delivery of manageable volume. If a 50. ml burette is used the volume to be delivered should be between 15. ml and 40 ml. The chosen concentration of NaOH means the concentration of NaOH that you would obtain if the tablets were pure, with the understanding the objective of the titration is to give you a more accurate measurement that you will use to calculate the purity of the tablet.

Acid-base chemistry tells us that the reaction between the hydronium and hydroxide ions is extensive and that the pH of the equivalence point should be close to 7. You will design a titration procedure indicating the reactants, the equipment, the data to be collected and the calculations. You will then proceed with two or three measurements depending on the precision of the first two. Your report will review the chemical background, present the data and the result and justify in your error analysis the number of significant figures of your reported concentration.

The average of the trial is 24. 3 mL. The molarity of NaOH was found by using the M1V1 = M2V2 equation, resulting in 1. 1 M of NaOH. Discussion In the Titrations Lab, 50. 0 mL of 0. M HCl and appropriate amount of NaOH were titrated to find the molarity of NaOH and the pH of the solution after x mL of NaOH has been added. The lab discussed the difference between equivalence point, the point at which the reaction between titrant and unknown is complete, and the endpoint, the point where the indicator turns color. The color change occurs when the concentration of more dominant form is ten times as great as the less dominant. However, color changes in a solution does not necessarily equal to the equivalence point.

Equivalence point can be found by observing the indicator, or using a pH meter and finding midpoint of vertical line in the titration curve. Endpoints can be found by observing the color change of the indicator. The titration lab also involved indicators. Indicators are substances which undergoes a color change in the pH interval of the equivalence point, allowing physical observation of pH change. Most indicators are weak acids, so protons shift from acid to conjugate base. The concentrations of indicators in a solution do not change molarity value.

You may also be interested in the following: back titration lab report

Spectrophotometry Essay

Spectrophotometry Essay

Potassium permanganate (KMnO_4) is commonly used as an oxidizing agent and in this experiment, it is used as both the titrant and indicator. A standard of potassium permanganate solution was prepared and computed to be 0. 02235 M and was used to titrate a sulfuric acid solution wherein the sample salt was dissolved. The solution was heated to 90°C then titrated until a light pink colored solution was obtained. The experiment focused on determining the percentage of Sodium oxalate (Na2C2O4) in the sample and at the end of the experiment it was found to contain 49.

45%. Experiment 9 focuses on determining the different concentrations of potassium permanganate solutions by finding its absorbance through the use of spectrophotometer. Four known concentrations were prepared; 2. 5 x ? 10? ^(-3) M, 6. 25 x ? 10? ^(-4) M, 1. 25 x ? 10? ^(-4) M, 6. 25 x ? 10? ^(-4) M. The solutions were placed on the spectrophotometer to determine absorbance together with the unknown. Distilled water was placed before each trial to ensure the accuracy of results.

Determining the concentration of the unknown sample was done by drawing a graph of the concentration against the absorbance and was found to be Introduction Spectrophotometry is a method to measure how much a chemical substance absorbs light by measuring the intensity of light as a beam of light passes through sample solution.

The basic principle is that each compound absorbs or transmits light over a certain range of wavelength. This measurement can also be used to measure the amount of a known chemical substance.

Spectrophotometry is one of the most useful methods of quantitative analysis in various fields such as chemistry, physics, biochemistry, material and chemical engineering and clinical applications. A spectrophotometer is an instrument that measures the amount of photons (the intensity of light) absorbed after it passes through sample solution. With the spectrophotometer, the amount of a known chemical substance (concentrations) can also be determined by measuring the intensity of light detected.

Chemistry investigation Essay

Chemistry investigation Essay

Aim: I am going to carry out an investigation measuring the rate of reaction between hydrochloric acid and magnesium. The independent variable will be the molar of the hydrochloric acid; I will be diluting it with water to change the concentration. The dependent variable could be one of four things; Temperature change, Mass loss, Gas produced using a burette or gas produced using a gas syringe. The dependent variable of the primary experiment will be decided once I have performed four preliminary experiments each with the different dependent variables.

The results of these preliminaries will help me determine which factor is the most accurate to measure.

Background Information: As I am planning to investigate the rate of reaction by changing the concentration of the acid I should take into consideration how the reaction is affected by concentration.

If there is more of a substance in a system, there is a greater chance that molecules will collide and speed up the rate of the reaction.

If there is less of something, there will be fewer collisions and the reaction will probably happen at a slower speed.

As you increase the concentration of the acid, there are more acid particles in the same volume. Therefore there is a greater chance of acid particles colliding, and reacting, with particles on the surface area of the magnesium ribbon.

Here is an example of how the rate of reaction will increase if the concentration gets higher:image00.png

With this in mind it is clear to see that as I decrease the concentrate of the acid by adding water to it I will be decreasing the rate of reaction. There is a positive correlation between the two variables.

The experiment equation that will effectively happen is:


Mg + 2HCl —- MgCl2 + H2

Magnesium; Magnesium is a light, silvery-white, and fairly tough metal. It tarnishes slightly in air, and finely divided magnesium readily ignites upon heating in air and burns with a dazzling white flame. Because serious fires can occur, great care should be taken in handling magnesium metal, especially in the finely divided state. Water should not be used on burning magnesium or on magnesium fires.

Hydrochloric acid; Hydrochloric acid is the aqueous solution of hydrogen chloride gas (HCl). It is a strong acid, the major component of gastric acid, and of wide industrial use. Hydrochloric acid must be handled with appropriate safety precautions because it is a highly corrosive liquid.

Hydrogen; when mixed with oxygen across a wide range of proportions, hydrogen explodes upon ignition. Hydrogen burns violently in air. It ignites automatically at a temperature of 560. Another characteristic of hydrogen fires is that the flames tend to ascend rapidly with the gas in air.

Magnesium chloride; this is the name for the chemical compounds with the formulas MgCl2 and its various hydrates MgCl2 (H2O) x. These salts are typical ionic halides, being highly soluble in water. The hydrated magnesium chloride can be extracted from brine or sea water. Anhydrous magnesium chloride is the principal precursor to magnesium metal, which is produced on a large scale.

Preliminary experiments:

Method: In this preliminary experiment I choose not to alter anything but to observe how the temperature increased within the time of the reaction. I used 10ml of hydrochloric acid and 3cm of magnesium ribbon. I carried out three repeat measurements to gain an idea of what the results would look like if compared.

Evaluation of Preliminary Methods

Each of the experiments above has limitations that strongly influenced the results. This has given me an idea of what degree of accuracy each method can be measured to and if they are suitable to collect data for the primary experiment.

Temperature: Measuring the temperature is a simple way of seeing where the rate of reaction begins, peaks and ends. It is a clear indication to how the magnesium reacts and at what temperature. There are, however, some inaccuracies to the formation of the set up. Some of the thermal energy detected by the thermometer is sometimes transferred into the glass of the conical flask which led to an inaccurate reading. Furthermore the thermometer is slow to respond to the rise in temperature and also only gives reading in whole numbers so slight elevations in heat are difficult to read and thus inaccurate.

Mass Loss: Measuring the mass at different points in the experiment provides markers to see how much magnesium and hydrochloric acid has been reacted. The electric scale I used was too sensitive to get a general reading; this affected the results severely. The mass would sometimes increase during the reaction due to a small piece of debris getting onto the scale or because a gust or air; consequentially the results were askew.

Gas Produced using a burette: This is a very good way of measuring the rate of reaction. The measurements are clear and can be recorded to a decimal place which makes the results very accurate. There are some limitations, however, to using a burette. When the gas is produced it takes time for the hydrogen to travel along through the tube and up into the burette. This extends the time of the reaction slightly because not all the gas has been collected which the magnesium has been dissolved. Furthermore some amount of hydrogen have escaped the burette and simply floated to the surface of the water not being accounted for. This is a small inaccuracy but can still alter the results.

Gas Produced using a gas syringe: This is a very accurate piece of equipment. It does not allow for gas to escape and records the data consistently and with speed. The only limitations in using a gas syringe are that the reading can only be reading in whole numbers and that the syringe sometimes collects water vapour as well. The water vapour, however, can be eliminating by adding an extra conical flask to the tube which collects the vapour as it is slightly cooler.

The gas syringe is the most advanced piece of equipment in each of the preliminary methods and also is the most accurate in recording the data. Therefore to calculate the rate of reaction between magnesium and hydrochloric acid my dependent variable will be the gas produced using a gas syringe.

Hypothesis: Now that I have determined what I am going to measure and how I can now make my prediction over what I think will be the final outcome of the experiment.

Rate of reactions are all based on the collision theory. This states that the more collisions in a system, the more likely combinations of molecules will occur. As a result of this the reaction will accelerate, and the rate of that reaction will increase. The concentration of a substance will raise the number of collisions and thusly speed up the rate of reaction.

On this basis I believe that if the molar of the hydrochloric acid is decreased there will be less gas produced and so the rate of reaction will slow. Here is a diagram:


We can see in the figure above that if the molar is halved then there are fewer particles in the water so fewer collisions can happen. The gas produced will therefore be reduced and the overall time of the reaction will decrease.


Variable controlled

How it is controlled

Why it is controlled

Concentration of Magnesium

By measuring out a 3cm piece of magnesium each time I take a repeat measurement.

I am measuring the concentration of the hydrochloric acid not the magnesium.

Concentration of Hydrochloric acid

I will start with 10ml of hydrochloric acid and replace 2ml of it with water every time I want to reduce the concentration.

I want to observe what effect it will have on the rate of reaction.

Water Vapour

Adding an extra, cooler conical flask to collect the water vapour.

I am measuring the gas produced between hydrochloric acid and magnesium; water vapour is not a product.


By putting the flasks in a thermostatically controlled water bath for 5 minutes before each experiment.

I am measuring the concentration and do not want the higher temperature to give the particle more energy to collide.


500ml conical flasks- To hold the magnesium and hydrochloric acid reaction and to collect the water vapour.
Conical flask bung (with hole for tubing) – To allow for gas only to travel through the tubing.
Glass tubing- To direct the flow of gas.
100 ml² gas syringes- To measure the gas produced.
Retort stand- To hold the gas syringe.
Clamp- This is attached to the retort stand.
50 ml measuring cylinder- To measuring the hydrochloric acid accurately
stop-clock- To measure the time of the reaction
10ml of Hydrochloric Acid plus varying amounts of water- To measure the concentration of the acid
Magnesium ribbon (3cm per experiment) – To react with the acid.
Ruler and scissors – To measure and cut the magnesium ribbon.

Here is a diagram:

Other apparatus: image10.pngimage09.pngimage11.png


Obtaining precise and reliable results

My experimental design permits me to take very accurate measurement; however, the only fault in its design is that the syringe only measures in whole numbers. This should not pose as a problem because I will take lots of reading to compensate. I will then find the mean of easy set of results so that I can compare them accurately in addition to this I will also take the range of the results which will allow me to observe whether they overlap.

The limitations of my other apparatus are common. Although my stop can measure to a 10th of a second my reaction time will be a lot slower then this. The ruler and scissors should also be taken into consideration, measuring and cutting the magnesium could cause some variation. The measuring cylinder also has to be estimated to a rough degree when pouring the hydrochloric acid. All of these small inaccuracies can add up to a large error so I need to be very consistent so each result is rounded to the same degree of accuracy.

Risk assessment: during the practical various measures must be taken to ensure the experiment is carried out safely. These measures are;

• Always wear safety goggles (at all times) to ensure no chemicals make contact with eyes.

• Wear laboratory aprons to ensure there are no spillages onto clothing.

• Use a bench mat to stop spillages onto bench

• Avoid contact of acid on skin – it is corrosive. If acid does touch skin it must be immediately washed off.

• Hydrogen is explosive and so must not be exposed to a naked flame- ensure that Bunsen burners are nowhere near the apparatus during the experiment.

• Basic Laboratory Rules i.e. do not run in labs, No food or drink allowed etc.

• No concentration of hydrochloric acid greater than 2 molar, anything larger is dangerous.

De-Scalers Essay

De-Scalers Essay

When water is heated limescale deposits can form, especially in machines such as fully automatic coffee makers, espresso machines and all hot water units. In this context you often hear about hard and soft water. The hardness of the water indicates the proportion of limescale. Your water supply company will provide more information about hardness of your water. If your groundwater flows through calcareous rock layers, eroded magnesium and calcium carbonate will cause limescale deposits in your water. Why do I need to remove limescale?

In addition to loss of coffee flavor limescale deposits can severely damage your machine and shorten its lifespan significantly.

Limescale deposits in your machine lead to: Longer scalding time with higher electricity charges Lower water temperatures causing inferior coffee flavor Blocked machines pipe Corrosion of metal parts and sealing gaskets Expensive repairs Only regular and timely descaling with a high-quality descaler, such as ceragol ultra Premium Descaler, ensures a long lifespan and optimal coffee flavor. Your coffee maker is a high-tech machine which needs regular, gentle care.

What do you expect from your descaler? Limescale deposits are removed by acids in the descaler. Only the right mixture of effective acids and gentle additives for the metal parts and sealing gaskets allows for optimal results during descaling. The quick reaction time and immediate reusability of the machine after rinsing are basic demands on a premium descaler. Why amidosulfonic acid? Descaling with citric or acetic acids The big problem when descaling with citric or acetic acids are the released flavor additives which cause an obtrusive smell during descaling.

The plastic parts of your fully automated coffee maker tend to taken on these smells and influence the smell and taste of your coffee negatively. Plastic parts and sealing gaskets of your unit can be attacked by the vinegar or acetic acid. Citric acid tends to flake during descaling. This can block the valves and water pipes and lead to high repair charges. An additional problem is that the limescale is actually sealed in by an indissoluble layer which occurs repeatedly when using descalers based on citric acids.

Descaling with vinegar, acetic acid or citric acid takes significantly longer than descaling with ceragol ultra Premium Descaler. Descaling with amidosulfonic acid Descaling with amidosulfonic acid, the active ingredient of our ceragol ultra Premium Descaler, does not require any reaction time. During the descaling program the limescale is dissolved and flushed away. This process is completely odorless and neutral in taste. After thorough rinsing your machine is once again food-safe. The additives in ceragol ultra Premium Descaler guard and protect the metal and plastic components of your fully automatic coffee maker.

The right time to descale Automatic coffee machine w. auto descaling indicator Please ask your water supply company about the hardness of your water and set the water hardness according to the operating instructions of your manufacturer. Your machine will indicate when descaling is needed. Automatic coffee machine w/o descaling indicator Descaling becomes necessary as soon as you notice a delay in operation or irregularities during coffee preparation. Another telltale sign is the reduction of the amount of foam produced on the coffee. The machine must be descaled periodically and in due time.

Who have to deal with loss Essay

Who have to deal with loss Essay

These shoes are a symbol of the daughter, “One shoe pointed in fact towards the bedroom window… and the other pointed towards the door. They wanted to get out” The writer has used personification here to suggest how the mother is trying to figure out why her daughter has left her, just like in “Chemistry” where the narrator misunderstands the mothers motives to set out for a new life. The boy mistakes “this look of relief, as if she had recovered from an illness.

” As if she did not care about the grandfather. The mother in “Your Shoes” makes the reader sympathize for her.

In this way, we see how the character of the mother is presented in the manner she deals with loss. The shoes are abandoned and this suggests that these shoes are a metaphor of the rejected parents. In comparison the structure that both the writers have used are that the stories are written in non- chronological order.

In “Your Shoes” the mothers thoughts flit backwards and forwards the mother does not deal with her loss and neither does she come to terms with it. Just like in “Chemistry” although the boy witnessed a lot he does not share his feelings.

It is clear when “Mother said: ‘He’s only ten what can he know? ‘” the boy certainly knows a lot more than he is credited for. Furthermore the stories “Your Shoes” and “Chemistry” are both written from the 1st person which then only shows the thoughts of the main characters so the readers may have to work out for themselves how the characters feel although it is fairly obvious in “Your Shoes”. In this way, we see that the writers have presented the way the characters deal with their losses differently.

The themes explored in both stories is conflict as in “Your Shoes” the father deals with the situation by calling his daughter “a dirty slut” and actually makes the situation worse, which is equal to “Chemistry” where the grandfather comes between Ralph and the mothers relationship. The theme of change is also mentioned in the stories as the mother is not prepared to face anything different, “I’ve taken a week’s sick leave from school” she does not want to go back without her daughter, but instead she wants everything back to how it was.

Whereas the boy in “Chemistry” is perhaps not ready but is forced to change the way he lives. The ways these characters deal with loss differ greatly. The setting in “Your Shoes” is of the mother “lying curled up in the middle of the bed” here the mother’s surroundings reflect the presence of her daughter. The mother is almost like a foetus, weak and unable to look after herself. The room symbolizes her daughter just like her shoes. In contrast the setting in “Chemistry” symbolizes the relationships drifting apart between each generation, “she had grown neglectful of Grandfather”.

Here Swift is describing the invisible thread that is holding the family together is shifting. The setting in these stories symbolizes how the characters in each story deal with loss. The setting in these stories symbolizes how the characters in each story deal with loss. To conclude I think that the main difference between the stories “Your Shoes” and “Chemistry” is that the mother does not come to conditions with the way she deals with loss. Whereas in “Chemistry” the boy realizes that dealing with loss is part of your life. ??

Gravimetric Analysis Essay

Gravimetric Analysis Essay

The purpose of experiment 1, also named Gravimetric Analysis, is to study the use of analytical chemistry. Analytical chemistry is a branch of chemistry that involves determining what matter is and how much of it exists. It is the science of separating, identifying, and determining the components that make up a compound and determining a specific amount of that compound. There are two types of analytical chemistry: qualitative and quantitative. This experiment uses quantitative analysis to determine the amount of a substance, or several species, and measure it in numerical terms.

More specifically, this experiment uses gravimetric analysis, a form of quantitative analysis that uses an analytical balance, an instrument that yields accurate and precise data, to measure the masses of several substances. Experiment 1 involves the precipitation of a complex compound called aluminum 8-hydroxyquinilinate, also called Alq3. In order for this precipitation to occur, an organic precipitating agent, 8-hydroxyquinilinate (abbreviated OxH) is used to react with aluminum ions to form this complex compound.

For this reaction to take place, OxH must be deprotonated, so that its anion, Ox-, will bond with the aluminum ions (the OxH molecule itself will not react with aluminum ions). As a result, the pH of the solution has a major effect on the precipitation in this experiment. If the pH is too low and there is an excess of hydrogen ions, then by Le Chatelier’s principle, the equilibrium will shift to the left, creating more OxH molecules.

Ox- will no longer be available and a precipitation will not occur. If the pH is too high and there is an excess of hydroxide ions, the aluminum ions will react with the hydroxide ions. There will be no aluminum to react in the precipitation. If the pH is neutral, OxH is not very soluble and may cause it to precipitate out itself. So in order for this precipitation in this experiment to take place, it is vital that a buffer solution of ammonium acetate is used to control the pH of the solution.

Also, the less aluminum ions in the solution, the more it will precipitate. In order to do this, an excess of OxH is added to shift the reaction towards the precipitate form. However, OxH has a limited solubility in water, so too much of an excess cannot be added. In order for the precipitate to work best in this experiment, we would have to allow it to digest. This lets use filter the precipitate completely. We do this by drying the precipitate in an oven and letting it age overnight.

This promotes the formation of fewer, larger, and more pure particles of the precipitate. In the end, we are trying to find the concentration of aluminum in the solution (millimole of aluminum per mililiter of solution). We do this by converting the mass of the precipitate into moles and using mole-to-mole ratio and stoichiometry; we find the moles of aluminum ions. We then divide this by the volume of the solution to find the molarity, or concentration, of the aluminum ions.

Investigating the strength of Electrolytic solutions Essay

Investigating the strength of Electrolytic solutions Essay

Table 1 above shows the raw data of experiment I did to test the strength different electrolytic solutions.

Moreover, this data table shows that all solutions except tap water and distilled water have the concentration of 0.5 M. In this table, some solutions’ ammeter reading has different uncertainty and multimeter setting. This is because solution like hydrochloric acid has high amp, so I had to set multimeter setting at 300mA in order to measure the ammeter reading of hydrochloric acid accurately.

On the other hand, solution like distilled water has extremely low amp, so I had to set multimeter setting at 0.

3mA in order to measure the ammeter reading of distilled water accurately. Hence, varying in uncertainty of reading in each solution because as 1 reading, for example, if measured at setting of 300mA, is 5 amp per reading but if measured at 0.3mA, it is read as 0.005 amp per reading.

2.1. Data Processing


Table 2 is a processed data of experiment on investigation of the strength of different electrolytic solutions. I included average of the data about strength of each electrolytic solution to make the data table clearer. Furthermore, I also included standard deviation of the data, to summarize the spread of values around the mean. Lastly, I added additional information about these solutions, whether if they are acidic, basic or neutral solutions.

3.1 Conclusion and Evaluation



To conclude, the background information that was given to me by the instructor states that stronger acidic or basic solutions are stronger electrolytes than those of weaker acidic, basic or neutral solutions. Referring to Table 2, which is a processed data of acquired data from this experiment, it provides the information of solutions whether if they are acidic, basic or neutral. In addition, it shows that stronger acid and base tend to have higher ammeter reading and weaker acid and base or neutral solutions tend to have lower ammeter reading. For example, hydrochloric acid, which is a strong acid, transferred mean reading of 47amp, whereas acetic acid, which is a weak acid, transferred mean reading of 0.92amp. Therefore, the results I got through experiment yield to the background information given by the instructor. (NakanishMasaki)



Everytime I finished experimenting with one solution three times, I thoroughly washed plastic container and 2 carbon electrodes with tap water, which made direct contact with the solution while testing, and dried them with paper towel. The purpose is to avoid errors in results by preventing mix of preexisting solutions with another kind of solution. Moreover, since the fluctuation of the value that multimeter presented made hard for me to decide what to write as the data, whenever I fully connect complete electrical circuit, I waited for 15 seconds for the fluctuations to ease down. Finally, when I was performing experiment on calcium hydroxide (Picture 1), I mixed it by stirring with the glass pipe in order to uniformly spread the substance that was deposited on the bottom of the solution, so I can get uniformly mixed calcium hydroxide.

I did my best to cover up the weaknesses of lab equipment, but there still are some weaknesses still which were present throughout the lab, and it might have varied the data I collected. First of all, in order to follow the written instruction from the instruction sheets given, I had to wash equipments that made direct contact with the solution everytime I’m changing the solution that I will perform experiment upon with distilled water, but due to the lack of distilled water, I washed them with tap water instead.

Second of all, I am not sure if 15 seconds were enough time for the fluctuations of the value to settle, or maybe it was too much time. Last of all, whenever I finish mixing the calcium hydroxide, I have to transfer the solution to the smaller beaker for measurement, but it takes time to do that and the substance might have been settled down within the calcium hydroxide solution. Therefore, there were some errors that prevented me from collecting the best results.

Improvements can be made by providing each candidate, like me, with better lab equipments such as more advanced multimeter. Also, enough distilled water so I can wash equipments with it to follow the original instructions given.

Works Cited




Chemistry Soya Milk Essay

Chemistry Soya Milk Essay

This project has been chosen in view of increasing demand of milk and also due to higher expectations of good quality and low fat diet requirements of the people with better awareness. Also the requirement for such quality products is more acute today. In this project I have prepared soy milk from soyabeans and have compared the conditions of formation of good quality cow milk yogurt and soy milk yogurt. I have also tried to find the effect of temperature on the pH of cow’s milk and soy milk.

Thus I have selected this project to find a suitable replacement of cow milk in soy milk to meet the demands of the ever increasing population. SOY MILK: Soy milk (also called soya milk, soymilk, soybean milk, or soy juice) and sometimes referred to as soy drink/beverage is a beverage made from soybeans. A stable emulsion of oil, water, and protein, it is produced by soaking dry soybeans and grinding them with water.

Soy milk contains about the same proportion of protein as cow’s milk: around 3. 5%; also 2% fat, 2. 9% carbohydrate, and 0. 5% ash.

Soy milk can be made at home with traditional kitchen tools or with a soy milk machine. The coagulated protein from Tofu, just as soy milk can be made into made into cheese. Soy milk can be made from whole soybeans or full-fat soy flour. The dry beans are soaked in water overnight or for a minimum of 3 hours or more depending on the temperature of the water. The dehydrated beans then undergo wet grinding with enough added water to give the desired solids A can of Yeo’s soymilk, poured into a glass. Soy milk can be made from soya beans or full flat soy flour. The dry beans are soaked in water for a minimum of 3 hours.

The dehydrated beans then undergo wet grinding with enough added water to give the desired solid content to the final product. The ratio of water to beans on a weight basis should be about 10:1. The resulting slurry or puree is brought to a boil in order to improve its nutritional value by heat inactivating soybean trypsin inhibitor, improve its flavor and to sterilize the product. Heating at or near the boiling point is continued for a period of time, 15-20 minutes, followed by the removal of an insoluble residue by filtration. SOY YOGURT – Soy yogurt looks like regular cream yogurt.

Soy yogurt, (Soya yoghurt in British English) also referred to as Soygurt or Yofu (a portmanteau of yoghurt and tofu), is yogurt prepared using soy milk, yogurt bacteria, mainly Lactobacillus bulgaricus and Streptococcus thermophilus and sometimes additional sweetener, like fructose, glucose, or raw sugar . It is suitable for vegans, as the bacteria for shop-bought soy yogurt are usually not grown on a dairy base. Soy yogurt can be prepared at home using the same method as dairy yogurt. One tablespoon of sugar per 1 liter of unsweetened soy milk may be added to promote bacterial fermentation.

Soy milk on its own lacks the lactose (milk sugar) that is the basic food for the yogurt bacteria. Soy yogurt may have a slight beany soy taste when made directly from freshly prepared soymilk, but this is less pronounced in shop-bought soy yogurt and in soy yogurt made from commercial soy milk. Soy yogurt contains less fat than yogurt made with whole milk. This amounts to about 2. 7% (the same percentage as soy milk), versus 3. 5% in dairy yogurt. However, dairy yogurt can be made with 2%, 1%, or fat-free milk, and these cases, it is lower in fat than soy yogurt. Cow Yogurt

Yogurt, also spelled yoghourt or yoghourt, is a favorite breakfast, lunch, or snack. A thick, custard- or pudding-like food, yogurt is made by the natural bacterial fermentation of milk. The process of making yogurt involves culturing cream or milk with live and active bacterial cultures; this is accomplished by adding bacteria directly to the milk. Commercially made yogurt is usually made with a culture of Lactobacillus acidophilus and Streptococcus thermophilis. Yogurt made at home is usually started by adding a dab of commercially made yogurt to boiled milk, and then keeping the mixture at 45°C.

In Western cultures, yogurt is enjoyed in a variety of ways, most popularly as a cool dish mixed with fruit. Yogurt can be used to make healthy shakes or frozen to eat like ice cream. Yogurt can also be used when cooking, in place of milk, sour cream, and even some cheeses. In Middle Eastern cultures, yogurt is frequently served with meat, meat sauces, and vegetables, It can be mixed with various other sauces or used as a tangy dollop on top of a meal. NUTRITION AND HEALTH INFORMATION Nutrients in 8 ounces (250 ml) of plain soymilk.

| Regular | Life Whole | Fat |kcal) | Soymilk | Soymilk cow (reduced milk fat) | Free cow milk | 90 | 70 149 | 83 | | 10. 0 | 4. 0 7. 7 | 8. 3 | | 4 | 2. 0 8. 0 | 0. 2 | | 14. 0 | 16. 0 11. 7 | 12. 2 | (g) | 0. 0 | 0. 0 11. 0 | 12. 5 | | 120 | 100 105 | 103 | (mg) | 1. 8 | 0. 6 0. 07 | 0. 07 | | 0. 1 | 11. 0 0. 412 | 0. 446 | (mg) | 80. 0 | 80. 0 276 299 | in 100 ml of fortified soyrpilk “Alpro Soya” versus semi skimmed and fat free milk: | | Enhanced Semi Fat free Soymilk skimmed cow cow milk milk | Calories (kcal) | 31 47 35 | Protein(g) | 3. 3 3. 6 | 3. 6 | Carbohydrate | 0. 2 4. 8 | 4.

9 | Lactose (g) | 0. 0 4. 8 | 4. 9 | Fat(g) | 1. 8 1. 8 | 0. 3 | Saturated fat | 0. 3 | 1. 1 | 0. 1 | Sodium (rng) | 10 | 44 | 5 | Iron (mg) | 0. 24 | 0. 02 | 0. 03 | Calcium(mg) | 120 | 124 | 129 | Vitamin A (mcg) | 1. 0 | 6. 0 0. 9 | 3. 5 0. 4 | VitaminBl2(mcg) | 0. 38 | Vitamin D (mcg) | 0. 75 | 2. 5 | 0. 0 | CHEMISTRY INVOLVED Proteins are chains of amino acid molecules connected by There are 22 different amino acids that can be combined to form protein chains. There are 9 amino acids that the human body cannot make and must be obtained from the diet.

These are called the essential amino acids. The amino acids within protein chains can bond across the chain and fold to form 3-dimensional structures. Proteins can be relatively straight or form tightly compacted globules or be somewhere in between. The term “denatured” is used when proteins unfold from their native chain or globular shape. Denaturing proteins is beneficial in some instances, such as allowing easy access to the protein chain by enzymes for digestion, or for increasing the ability of the whey proteins to bind water and provide a desirable texture in yogurt production.

The main (starter) cultures in yogurt are Lactobacillus bulgaricus and Streptococcus thermophilus. The function of the starter cultures is to ferment lactose (milk sugar) to produce lactic acid. The increase in lactic acid decreases pH and causes the milk to clot, or form the soft gel that is characteristic of yogurt. The fermentation of lactose also produces the flavor compounds that are characteristic of yogurt. REQUIREMENTS Beakers, pestle and mortar, measuring cylinder, glass rod, tripod-stand, thermometer, muslin cloth, burner.

Soya beans, cow milk, fresh curd and distilled water, pH papers. PROCEDURE 1) Soak about 150g of Soya beans in sufficient amount of water so that they are completely dipped in it. 2) Take out swollen Soya beans and grind them to a very fine paste 3) Filter it through a muslin cloth. Clear white filtrate is soya bean milk. Compare its taste with cow milk. 4) Take 50 ml of soya bean milk in three other beakers and heat the beakers to 300, 40°and 50°C respectively. Add ? spoonful curd to each of these beakers. Leave the beakers undisturbed for 8 hours and curd is formed.

5) Similarly, take 50 ml of cow milk in three beakers and heat the beakers to 30°, 40° and 50°C respectively. Add ? spoonful curd to each of these beakers. Leave the beakers undisturbed for 8 hours and curd is formed. 6) Take 20 ml of cow milk and soya bean milk in two separate test tube and test OBSERVATION TYPE OF MILK| BEAKER NO| TEMPERATURE. C| TIME TAKEN TO FORM CURD(HRS)| TASTE OF CURD(AFTER 8 HRS)| COW’S MILK| 1| 30| 6. 5| SWEET| | 2| 40| 5| SOUR| | 3| 50| 4| SOUR| SOY MILK| 4| 30| 8. 5| NOT FORMED| | 5| 40| 7| SWEET| | 6| 50| 6| SWEET| TYPE OF MILK| BEAKER NO| TEMPERATURE.

C| pH| COW’S MILK| 1| 30| 6| | 2| 40| 6| | 3| 50| 6| SOY MILK| 4| 30| 7| | 5| 40| 7| | 6| 50| 7| RESULT 1. For cow milk, the best temperature for the formation of good quality and tasty curd is 40°C and for soyabean milk, it is 50°C. 2. For cow milk, the pH of good quality and tasty curd is 5 and for soyabean milk, it is 6. INFERENCE Thus the formation of good quality soy yogurt the time taken was 7 hours for a sample at 50°C and at a pH value around 6. whereas, for the formation of good quality curd the time was 5 hours for a sample at 40°C and at a pH value around 5.

Thus a good yield of curd can be obtained with soy milk. And moreover soy yogurt helps in controlling type 2 diabetes and high blood pressure. The enzymes in the soy yogurt also help in regulating blood sugar levels. Thus soy milk is a suitable replacement of cow milk to meet the demands of the ever increasing population. INDEX Why I chose this project? 1 Soya bean milk 1 Soy yogurt 4 Nutrition and Health Information 7 Chemistry involved 9 Requirements 10 Procedure 11 Observations 12 Result 13 Inference 13 Bibliography 10 BY: Vishal Kamalakannan.