Categories for Experiment

Kinetics Lab Essay

Kinetics Lab Essay

How does the molar concentration of hydrochloric acid affect the rate of pressure in a gas releasing reaction?

The aim of this experiment is to record how the change in molar concentration of hydrochloric acid affects the rate of the reaction. The following reaction will be tested:

Na2CO3 10H2O + 2HCl –> 2NaCl + CO2 + 11H2O

To measure the rate of the reaction an Explorer GLX with a pressure sensor will be used. The pressure will be measured every second for 90 seconds.

Hypothesis:

I believe that if the molar concentration of the hydrochloric acid is increased, than the rate of the pressure will also increase. This is due to the fact that first of all, the reaction is a gas releasing reaction, and therefore more pressure will be built up in the flask. Also the more concentrated one of the reactants is the more particles there will be, resulting in more collisions between the particles.

Variables:

Type of Variable

Variable

Range of Values/Method of Control

Independent Variable

Concentration of Hydrochloric Acid

0.50 molar, 0.75 molar, 1.0 molar

Dependent Variable

Rate of kPa

Explorer GLX – records every second

Controlled

Mass of Sodium Carbonate-Deca-Hydrate

0.50 grams

Temperature of Reaction

All reactions occur at 22�C (room temperature)

Total Time of Reaction

90 seconds in all trials

Volume of Hydrochloric Acid

15cm3 in all trials

Materials:

* 250ml flask

* 1-hole stopper with gas collection tube

* 4.5 grams of sodium carbonate-deca-hydrate

0.5 for each trial (� 0.005g)

* Explorer GLX with pressure sensor (�1.75kPa)

* Laptop with Data Studio

* Stop watch (� 0.005s)

* 135ml of hydrochloric acid

45ml of each concentration (�1ml)

* Balance

Picture:

Method:

There will be three trials for each of the three different concentrations of hydrochloric acid. Using 9 weighing boats and the balance split the sodium carbonate-deca-hydrate into 9 sets of 0.50g.

1) First, set up the data studio and GLX explorer on the laptop. Once the pressure sensor is plugged in the GLX a blank graph should show up. Under “setup” in data studio, change the rate of measurement to every 1 second.

2) Pour 15ml of 0.5molar hydrochloric acid into the 250ml flask.

3) Click the play button on the GLX explorer to start the measurements, and immediately drop the 0.50 grams of sodium carbonate-deca-hydrate into the hydrochloric acid; right after cover the flask with the one hole stopper.

4) There should be a stop watch on the data studio software, and after 90 seconds stop the measurements by pressing play on the GLX explorer.

5) Save the file as 0.5molar trial 1.

6) Clean out the flask and repeat steps 1 through 5 two more times, for trials 2 and 3.

7) After three trials are recorded and saved for 0.5molar hydrochloric acid. Repeat these steps for 0.75molar and 1molar hydrochloric acid.

Overall, you will have a total of 9 different graphs on data studio. These graphs will later be interpreted by applying a tangent line to the beginning of each graph. This tangent line will show the rate of the reaction (sufficient relevant data).

Results:

The graphs from the GLX explorer are shown in the appendix at the end of the lab roport. A tangent line (slope line) was used on the beginning of the graphs to get the rate of the reaction. The slope of the tangent line would be the rate of the reaction at the point where the tangent line meets the curve.

Table 1: The Rate of the Reaction Concerning the Concentration of the Hydrochloric Acid

Concentration (moles) � 0.01m

Qualitative Results:

* The reaction released a lot of gas. I noticed this because at first the reaction was being done in a test tube and then the one-hole stopper popped off in the middle of the reaction, resulting in a switch to use a flask.

* When the molarity of the hydrochloric acid was higher, there was a much louder fizzing noise, indicating a faster reaction.

* For some cases no all the sodium carbonate-deca-hydrate reacted fully.

* Not all the sodium carbonate-deca-hydrate which was added to the hydrochloric acid was crushed to powder.

Graph:

Calculations:

Percentage Uncertainty:

Concentration:

(0.01/0.50) x 100% = 2.0%

(0.01/0.75) x 100% = 1.3%

(0.01/1.00) x 100% = 1.0%

Average Rate of Reaction:

(0.05/1.00) x 100% = 5.0%

(0.05/1.30) x 100% = 3.8%

(0.05/2.30) x 100% = 2.2%

Total Percentage Uncertainty: 15.3%

Percentage Error:

Using sodium carbonate deca hydrate was a limitation to this experiment beacsue this made it extreamly hard to calculate the theoretical value of the reaction. Therefore, one cannot tell weather the lab had a systematic error and a random error.

Conclusion:

Overall, the hypothesis held correct. Clearly shown from the results, the rate of the reaction was much faster when the molar concentration of the reaction was greater. The rate of the reaction was measured using a pressure sensor, and as the rate of the pressure would indicate the rate of the reaction. For the one molar concentration of hydrochloric acid the rate of the reaction was about twice as fast as the half molar concentration. This can clearly be explained through kinetics. The more concentrated one of the reactants is the more particles there will be. Therefore, when there are more particles more collisions will occur and with more collisions the chances of the collisions being greater than the activation energy will also increase. Overall this increases the rate of the reaction.

Evaluation:

Overall, this experiment went very well; however, there were numerous limitations which affected the results. One very clear and important limitation is the fact that not all the sodium carbonate-deca-hydrate was powder. During the experiment, 0.50 grams of sodium carbonate-deca-hydrate was collected for each trial of the experiment. However, not all the sodium carbonate-deca-hydrate was powder, as there were some larger pieces. This changes the surface area of the reactant and that would have a greater affect on the results.

For example, if one of the trials had 0.50 grams of sodium carbonate-deca-hydrate and there was a big piece of that substance, than the surface area of those 0.50 grams would be less than the surface area of the trial that had all powder substance. With a larger surface area there would be fewer collisions which would make the rate of the reaction slower. Directly affecting the results, this limitation would need to be improved. A realistic improvement to this experiment would be to simply use a bowl and crush all the sodium carbonate-deca-hydrate to powder. Therefore, there would be no big pieces and the surface area would be relatively the same in each trial.

Another limitation to this experiment would be the fact that the sodium carbonate-deca-hydrate was poured into the test tube right before the one hole stopper was placed on the test tube. Therefore, there was a small time frame where gas was lost. This would affect the pressure in the test tube. One simple way to improve this limitation would be to use a special test tube. with this special test tube there should be a small hole on the side where another tube comes out and that is where the sodium carbonate-deca-hydrate would be placed in. Therefore, there would be minimal or no gas escaping and the results would not be affected by a drop in pressure.

Indirect thermometric Titration Essay

Indirect thermometric Titration Essay

* School Name: Al Mashrek International School

* School Code: 2108

* Subject: Chemistry

* Topic: Indirect A thermometric Titration.

* Assessment: Data Collection, Data Processing & Presenting, Conclusion & Evaluation.

* Candidate Name: Bassam Al-Nawaiseh

* Date: 20/5/2007

* Aim:

The aim of this experiment is to determine the concentrations of two acids. The two acids are Hydrochloric acid, HCl, and Ethanoic acid, CH3CO2H. This will be done by thermometric titration, by calculating the enthalpy change for each reaction, enthalpy of neutralization.

* Data Collection:

Table 1: the temperature change for the HCl solution and CH3CO2H solution after adding 5 cm� portions of 1M NaOH on each acid.

* Data Processing & Presenting:

Graph 1: represents the temperature change in the solution when titrated with HCl after extrapolation.

Graph 2: Represents the temperature change of the solution titrated against Ethanoic Acid after extrapolation.

* From graph 1, it is shown that after extrapolating the final temperature of the solution are 38 �C instead of being 34 �C from the normal graph.

* From graph 2, it is shown that after extrapolating the graph, the final temperature of the solution is about 34 �C instead of being 32 from the normal graph.

* Amount of NaOH = c x v = 2 x 0.05 = 0.1 mol NaOH

* Amount of Heat Energy for HCL solution

= m x s x ?T = (100/1000) x 4.18 x (38 – 23) = 6.27 KJ

* Molar Heat Energy for HCL solution

= – 6.27 x (1 / 0.1) = – 62.7 KJ/mol

* Amount of Heat Energy for Ethanoic Acid Solution

= m x s x ?T = (100/1000) x 4.18 x (34 – 23) = 4.56 KJ

* Molar Heat Energy for Ethanoic Acid solution

=- 4.56 x (1 / 0.1) = -45.6 KJ/mol.

(Negative sign was added to both the heat energies because the reaction is exothermic due to the rise in temperature of the solution.)

* Conclusion & Evaluation:

* ?H neutralization for Ethanoic Acid (-45.6 KJ/mol) is lower than that for Hydrochloric Acid (-62.7 KJ/mol). This is because HCL is a strong acid which completely ionizes and dissociates. On the other hand, CH3COOH is a weak acid which partially ionizes in water.

* Percentage Uncertainties is:

* Pipette (Volume of NaOH):

(0.1/50) x100 = 0.20%

* Burette (Volume of HCL):

(0.05/50) x 100 = 0.10%

* Burette (Volume of CH3COOH):

(0.05/50) x100 = 0.10%

* Thermometer (Temperature of HCL):

(0.5/61) x 100 = 0.81 %

* Thermometer (Temperature of CH3COOH):

(0.5/57) x 100 = 0.87 %

* Total Percentage Uncertainty = 0.20+0.10+0.10+0.81+0.87

= 2.08 %

* Absolute Uncertainty for ?H HCL = 62.7 x (2.08/100) = 1.3

* Absolute Uncertainty for ?H CH3COOH = 45.6 x (2.08/100) = 0.94

* ?H Hydration for HCL is -62.7 KJ/mol (� 1.3)

* ?H Hydration for CH3COOH is -45.6 KJ/mol (� 0.95)

* Percentage Error:

1. Literature value for HCL is -57.6 KJ/mol

= (57.6 – 62.7)/57.6 = 0.0885 x 100 = 8.85 %

2. Literature value for CH3COOH is -36.8 KJ/mol

= (36.8 – 45.6)/45.6 = 0.193 x 100 = 19.3 %

* Errors:

1. Some heat was lost to the surrounding during the reaction. Water temperature decreased as a result from the heat loss, which caused a decrease in the final temperature.

2. The polystyrene cup was not covered with a lid, which also caused heat to be lost to the surrounding.

3. While stirring, the thermometer hit the bottom of the polystyrene cup which caused the thermometer to take the temperature of the cup instead of the water. This affected the readings of temperatures in different intervals which caused an error in drawing the graph.

4. Stirring of the solution was not constant all over the reaction, which caused a partial gain of heat.

* Improvements:

1. The polystyrene cup should be covered with a lid, which will increase its insulation and will decrease the amount of heat lost to the surrounding.

2. The thermometer should not hit the bottom of the cup when stirring and friction should be reduced to maximum. This can be done by either holding the thermometer accurately up from the bottom. Or by adjusting it into a clamp embedding it in the solution, while using a glass rod for stirring.

3. Stirring the solution should be constant all over the reaction in order to have accurate readings during all time intervals, which will make the graph and its extrapolating more accurate.

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An experiment to show Essay

An experiment to show Essay

To see whether there is a relationship between the surface area and the diffusion rate Hypothesis I predict that the smaller blocks of agar will turn clear, or diffuse first, as it has a smaller surface area. This is because there is less surface area and volume for the sulphuric acid to diffuse into. Apparatus  Three sizes of agar, 20x20x20mm, 20x20x10mm, 20x20x5mm 40ml of sulphuric acid [80ml per beaker] 3 100ml beakers  Tile used for placing the agar  Tissue to wipe off the sulphuric acid off the agar  3 scalpels  Ruler, measurable in mm.

Stop clock Method 1. First, cut three pieces of sulphuric acid in the following sizes 20x20x20mm, 20x20x10mm, 20x20x5mm, as accurately as possible 2. Next, fill the three beakers with 80ml of sulphuric acid each 3. Then, prepare the stop clock, and make sure it is has been reset 4. After, place the three blocks of agar into the sulphuric all at the same time, as well as starting the stop clock once the agar is in the sulphuric acid.

5. Carefully stir the three beakers using the scalpels. 6. Watch until one of the blocks have gone completely clear.

7. Once one of the blocks have gone completely clear, stop the stop clock and take out the three blocks of agar and place on the tissue, and wipe off the excess sulphuric acid from the blocks of agar to prevent further diffusion with the two other blocks which have not been fully diffused to fully diffuse 8. Cut the blocks in diagonal, through the middle and using a ruler, measure how much of it has turned clear on each side. 9. Record the data for time taken, and the depth of the clear part on the table. Results Block number 1 2.

3 Block dimensions/mm 20x20x20 20x20x10 20x20x5 Predicted order of clearing 3 2 1 Actual order of clearing 3 2 1 Time taken for clearing 8mn56. 29s Depth of clear part on block/mm 3 4 5 Surface area/mmi?? 2400 1600 1200 Volume/mmi?? 8000 4000 2000 Surface are to volume ratio O:O. 3 O:O. 4 O:O. 6 Conclusion My prediction as to which block will go clear first was correct, being the smaller block, as its surface area to volume ratio was the greatest out of all three, even though there was not much difference between the three values.

This is because the third block has a greater surface area for the sulphuric acid to diffuse into the agar, causing the diffusion rate to be greater. The blocks have become ‘clear’ through diffusion caused by neutralization between the sulphuric acid and the agar, which is an alkaline. Evaluation Quite a few things did not go as planned in this evaluation, but I have come up with ideas on how to improve them if we do an experiment like this again.

Firstly, the jelly size may not be accurate from cutting it, and when it has been stirred, bits of it may have chipped off causing a change in its surface area. Next time, to avoid this, we could measure the block of agar more accurately when cutting it, and also be more careful when stirring the agar and stir softer so that no bits may get chipped off. Not only that, but the time we place the three blocks of agar into the sulphuric acid may be different, as well as the time we started the stop clock.

Next time, we may possibly find a different method of putting in and taking out the agar so that it remains a fair test, and so that there are less mistakes in the test, which may be reduced by having one person per block of agar and beaker, as well as another person for the stop clock and placing it in and taking it out all at the same time as well as starting and stopping the stop clock. Another complication may have come from the amount of sulphuric acid in each beaker, which may not have been equal.

This problem may be reduced by measuring the sulphuric more carefully, maybe with a measuring cylinder before then placing it into the beaker, instead of measuring it into the beaker straight away. Our measurements of the depth of the clear layer of the blocks of agar jelly may have been incorrect as well, and to prevent this, we could possibly use a microscope next time and use a graticule to measure the depth that the jelly has diffused to obtain a more accurate result.

The last problem I noticed while doing the experiment was when we were blotting the sulphuric acid off the agar. I found that there may have been some sulphuric acid left on the agar after we have blotted it, which may have caused further diffusion and adjusting our result. This is caused from not blotting off enough sulphuric acid off the agar. Next time, we could carefully blot all the sulphuric acid, and use one piece of tissue for each block of agar so that there is no sulphuric acid on the tissue before blotting each block of agar.

Ecology Mock Experiment Essay

Ecology Mock Experiment Essay

Due to their large size oak trees become shelters and nesting sites to very many wildlife species, so if one were to remove or decrease availability of these oak trees then one might expect the abundance of the animals that use oak trees as a home would decline as well. In this experiment, we will be testing whether or not the availability of oak trees in an environment will affect the distribution and abundance of robins.

The hypothesis of the experiment would be as follows: The population size of robins is restricted by the availability oak trees present.

This hypothesis would then lead you to predict that by removing oak trees from an environment, the population size of robins would then decline.

In this experiment, both the control and the experimental groups will be tested in similar conditions which include temperature, geographic location, resources available, and species diversity and richness of the areas in which the experiments are taking place. The variable which will be tested is the presence of oak trees.

Therefore, the experimental group will have the oak trees removed while, the control group will have the oak trees present. For the experiment, we will observe these groups on a weekly basis for two months.

If in the experimental group, the population of the robins were to show a decline while population of the control group would remain at a steady pace over the two month span then my hypothesis would be proven correct. But if results of the experiment were to show the population size of the experimental group have similar numbers with the control group or show the control group’s robin population decrease more than the experimental group then my hypothesis would be disproven.

Chapter & Readings R Essay

Chapter & Readings R Essay

Chapter 9 readings this week is about experiments. The learning objectives in this chapter are the used for experimentation, advantages and disadvantages of the experiment method, seven steps of a well-planned experiment, internal and external validity with experiment research designs, and the three types of experiment designs and the variations of each. In chapter 9 experiments is defined as the studies involving intervention by the researcher beyond that required for measurement (McGraw-Hill Company). One of the advantages of experiments is that it comes the closest than any primary data collection to accomplish its goal.

One of the foremost advantages is the ability of the researcher to manipulate the independent variable. The second advantage of the experiment is the contamination of extraneous variables being controlled way more effectively in other designs.

This allows researchers to isolate the variable and evaluate the impact. The third is the convenience and cost experimentation that are superior to other methods (McGraw-Hill Company). The benefit of this is that it allows experiment opportunities in scheduling data collection and the flexibility in adjusting the variables.

The disadvantages are the artificiality of the laboratory of the experimental method. Second are the samples of nonprobability can pose problems despite the random assignment. Conducting a well-executed experiment must have a complete series of activities in order to have a successful experiment. In chapter 9 Exhibit9-1 it gives researchers seven activities that a researcher must accomplished in order to have a successful research. Exhibit 9-1

1. Seven relevant variables.
2. Specify the treatment levels.
3. Control the experiment environment.
4. Choose the experimental design.
5. Select and assign the subjects.
6. Pilot test, revise, and test.
7. Analyze the data.

Researchers are task to translate an amorphous problem that is being question or the hypothesis that is best state of the objectives the research (McGraw-Hill Company. The book mentioned that hypothesis is a relational state because it describes a relationship between two or more variables (McGraw-Hill Company). It also be operationalized, a term we used earlier in discussing how concepts are transformed into variables to make them measurable and subject to testing (McGraw-Hill Company). Researches challenges are: 1. Select variables that are the best operational representations of the original concepts. 2. Determine how many variables to test.

3. Select or design appropriate measures for them (McGraw-Hill Company). Controlling the experimental environment variables may appear in differences in age, gender, race, dress, communications competence, and many other characteristic (McGraw-Hill Company). Environmental Control is defined as holding contrast the physical environment of the experiment (McGraw-Hill Company). Other forms of experiment are the control of the subjects. Subjects that are that have no knowledge that they are receiving experimental treatment are said to be blind.

Double blind is when the experimenters do not know of the treatment of the experiment group or the control group. Experiment design is unique in the experiment method. As it serves as a positional and statistical plan to designate its relationship between the experimental treatments and experimenters observations (McGraw-Hill Company). When conducting an experiment the researchers apply their knowledge in order to select the design that is best suited for the goals research. When analyzing data if must have adequate planning. Researchers have several measurements and instrument options with experiments (McGraw-Hill Company). Observational techniques and coding schemes.

Paper-and-pencil tests.
Self-report instruments with open-ended or closed questions. Scaling
techniques
Physiological measures (McGraw-Hill Company).
Even though there are different types of validity the two major varieties that are considered are internal validity and external validity. Internal Validity among its many threats seven are consider: History

Maturation
Testing
Instrumentation
Selection
Statistical regression
Experimental mortality
External validity among its threats the following are its interactive possibilities: Reactivity of testing on X.
Interaction of Selections and X.
Other reactive factors.
References
Author Donald R. Cooper, Pamela S, Schindler. 2011 McGraw-Hill Comapny

Determining the position of unknown element X in the Reactivity Series Essay

Determining the position of unknown element X in the Reactivity Series Essay

To determine the position of Element X in the reactivity series

Hypothesis

The reactivity series is the arrangement of elements according to their reactivity. The most reactive element is placed at the top and the least reactive at the bottom. The elements at the top can displace elements below them from their compounds

In the experiment, element X will either have elements more reactive or less reactive or both. Based on this, the position of the unknown element can be found out.

Assuming that the element given is not potassium, then potassium will displace X from its compound; thus we can say that potassium is more reactive than X; and X is below potassium in the reactivity series. Assuming that copper is less reactive than X; X will displace copper from its compound. This means that X is higher than copper in the reactivity series than copper.

In the experiment, the enthalpy (temperature) change will also show how reactive element X is.

For example if X is right above Zinc in the reactivity series i.e. element X is aluminium, then the temperature difference between reacting Al with CuSO4 will be more than reacting Al with ZnSO4 or FeSO4. This is because as the distance (number of elements in between between) the elements increases there is more difference in the reactivity level of the selected elements.

When ?H (?Heat) is +ve, the reaction taking place is exothermic and when ?H is -ve, the reaction will be endothermic. When the number of element between the elements reacting is more, then ?H of the reaction will also be more. For example if we take Zinc as element X, then Zinc is more reactive than Lead; but Zinc is even more reactive than Copper. This is because Copper is further below Lead in the reactivity series. Thus a reaction between Zinc and a Copper compound will be more reactive (& will have a higher ?H) than a reaction between Zinc and Lead.

When ?E (?Energy) is +ve, the reaction taking place is endothermic and when ?E is -ve, the reaction will be exothermic. The reason behind the nature of ?H stated previously is the ?E (?Energy) of the reaction. Again; more the number of elements between the reactants (according to the Reactivity Series) the lower the value of ?E i.e. more exothermic the reaction is. This is due to the type of bonds present in various compounds. Taking the pervious example, a reaction between Zinc & a Copper compound will give a lower ?E than a reaction between Zinc & a Lead compound. Thus such reactions are more apparent.

Variables

Independent

The Metal Compound used to react with Element X

The metal compound used to react with Element X was varied as this variation of the metal will help us determine the position of element X.

Dependent

Whether a reaction takes place or not

When different metal compounds are used, it is not necessary that a reaction takes place every time. The occurrence of a reaction depends on the metal present in the compound used.

Energy Change (?E)

?E depends on the compound used. In different compounds there are different types of bonds present and also every bond has a different energy level.

Enthalpy Change (?H)

?H depends on ?E. If ?E is -ve, then the reaction is exothermic; if ?E is +ve, then the reaction will be endothermic.

Controlled

Volume of the Metal Compound taken

The volume of the metal compound taken must be kept constant as varying volumes can affect the final temperature.

Size of Element X strip

The size of the strip of Element X must also be kept constant as varying lengths can again affect the final temperature.

Apparatus

1 Strip of Element X

7 Test tubes

5ml of CuSO4

5ml of FeSO4

5ml of MgSO4

5ml of PbNO3

5ml of KSO4

5ml of AgNO3

5ml of ZnSO4

Procedure

1. Take a strip of Element X and cut it into 7 equal pieces

2. Pour 5ml of CuSO4 into a test tube

3. Put a thermometer into one test CuSO4 and measure the temperature

4. Now put a piece of Element X into the test tube and measure ?H

5. Repeat Steps 3 & 4 for FeSO4; MgSO4; PbNO3; KSO4; AgNO3 & ZnSO4

Diagrams

Results

Compound

Reaction

Initial Temperature (�C)

Final Temperature (�C)

?H (�C)

KSO4

No

21

21

0�

MgSO4

No

21

21

0�

ZnSO4

No

22

22

0�

FeSO4

No

21

21

0�

PbNO3

Yes

21

22

2�

CuSO4

Yes

22

25

3�

AgNO3

Yes

21

26

5�

Graph

Discussion

The strip of element X given to us was shiny, this indicates that element X is not very reactive. Reactive metals such as aluminium usually form a metal oxide layer on top of them thus losing their luster. When Element X was put in sulphate of potassium (which is a clear solution), the solution remained clear, and the piece of Element X also remained shiny; thus indicating no reaction. Element X behaved similarly for sulphates of Magnesium, Zinc & Iron.

A piece of Element X into PbNO3, after a lot of time, the solution started to become cloudy (white precipitate), indicating a reaction. In this reaction the ?H was +1�C.

In CuSO4, the piece of Element X was deposited with black precipitate all over. Also the solution becomes lighter blue as compared to the pure CuSO4(aq). It was a very slow process.

In AgNO3, the solution turned cloudy (black) immediately after suspending the piece of Element X.

If we observe the table below carefully, we notice that Element X did not react with K, Mg, Zn and Fe. But it reacted with Pb, Cu & Ag. This means that element X is Sn; because the reactivity series goes as follows: K, Na, Ca, Mg, Al, Zn, Fe, Sn, Pb, Cu, Ag, Au.

Compound

Chemical Equation

Energy Equation

?E

KSO4(aq)

MgSO4(aq)

ZnSO4(aq)

FeSO4(aq)

Pb(NO3)2(aq)

CuSO4(aq)

AgNO3(aq)

As I stated in my hypothesis, that the further apart the elements are (in the Reactivity Series) the lower the ?E is. This means that the reactions are more apparent (vigorous) and also more heat is produced in such reactions.

Conclusion

From this experiment, I conclude that the Element X given to me is below Iron and above Lead in the reactivity series i.e. the element is Tin. I also conclude that the further apart the elements are (in the Reactivity Series) the higher the ?H and lower the ?E. I also conclude that such reactions are more reactive (apparent) as compared to those between element with a lower number of elements between them.

Evaluation

In this experiment, if the mass of element X would have been measured and then used for reactions the reactions would have been more accurate and reliable.

Molar Volume of a Gas Essay

Molar Volume of a Gas Essay

Introduction:

In this lab I am going to find out the volume of one mole of hydrogen gas at room temperature and atmospheric pressure. The room pressure only slightly differs from the standard, but can be taken into consideration when calculating the results. The molar volume is 22.41 liters per mole at STP (Standard pressure), in other words, at zero degrees centigrade.

Figure 3.1 (the experiment set up)

Procedure:

1. Set up all equipment.

2. Cut a piece of Magnesium ribbon about 20cm in length.

3. Calculate the weight of the ribbon from the weight of a 1 m long ribbon.

4. Measure 1.0 M Hydrochloric acid to a volume of 25-30ml.

5. Pour the HCl to the reaction flask.

6. Add the Mg ribbon to the reaction flask and secure the mouth of the flask as fast as possible with a hose. Make sure that the hydrogen gas cannot escape from the flask.

7. Follow the temperature

8. Collect the gas until no further reaction is observed in the reaction flask.

9. Carefully remove the gas collection flask so that no gas escapes from the flask.

10. Light the gas.

11. Determine the volume of the gas.

12. Calculate the molar volume of H2 gas at room temperature.

a) theoretical value from Vm =22.44 l/mol at STP.

b) experimental value from your data.

Equipment:

* 2 flasks (volume at least 600ml)

* large container (volume at least 3,5 l)

* Magnesium ribbon

* 30ml of Hydrochloric acid

* thermometer

* a hose (to cover the reaction flask)

Observations:

* Magnesium ribbon was a little oxidized for it had lost some of its shine.

* When the collection flask was turned around and placed in the water filled container, there were tiny air bubbles on the inside walls of the flask.

* When Magnesium ribbon was added, it began to corrose in the HCl

* Instantly after adding the Mg ribbon to the hydrochloric acid, temperature in the reaction flask started to rise as a chemical reaction took place in the flask.

* Moisture and (fog) blocked the view of the reaction

* Immediately after adding the Mg ribbon, hydrogen bubbled to the collection flask

* Hydrogen bubbled to the flask for about a minute,stopping soon after the ribbon had corrosed in to the HCl.

* There was a hissing sound as the chemical reaction occurred in the reaction flask and the gas flowed to collection flask through a pipe.

* The temperature in flask A rose quickly by a few degrees celsius and then stayed nearly constant for the 15 minutes the temperature was measured.

* The temperature did not change in flask B;however, it cannot be stated for sure as it was only compared with the temperature of flask A.

* The temperature in flask A rose very quickly as the reaction started

* The amount of hydrogen produced from the reaction was large for large bubbles of gas rose to beaker B within few seconds after starting the experiment

* The volume of the reaction flask was not measured, but it is close to the volume of the other flask (629ml)

* After the reaction, when lighting the hydrogen gas, collection beaker made a popping sound but the reaction flask actually burned and formed a thin flame.

* The flame from the reaction flask gave out a lot of heat, which was not noticed when lighting the gas in the collection flask.

Theoretical = 22.5 l/mol

Vm= 22.41

0.36 % error

The molar volume was 0.36% too large. The error can come from

– water vapour in the collection flask

– 10cm water below the glass

– air in the collection flask

– temperature rise in the reaction flask

– water vapour in the reaction flask

Evaluation:

This experiment had many error-causing factors, which probably influenced the results. Overall, the calculations showed that very little error (0.36% error) which made me a little skeptical about the results. Such a small error percentage was not expected.

To point out a few mistakes, I did not measure the difference in height of the water level from the surface of the water-filled container. This would have allowed further investigation about the volume of hydrogen in the flask. Also, the exact volume of the reaction flask was not measured. It was only stated by eye that the flasks looked to be the same size.

Other than that, the experiment was performed well. It was made sure that none or very little air was left in the collection flask when turning it around and placing it in the water filled container. There were a few tiny air bubbles on the walls; however, the air in the reaction flask was more likely to influence the result. Having a lab partner helped with managing time, for one was able to follow the temperature while the other checked the time. We made sure that we had read the instructions carefully and thought twice before deciding what methods to use when, for example, turning the flask upside down in the water.

Conclusion: In conclusion, the experiment turned out some successful results. When magnesium reacted with the hydrochloric acid, hydrogen was released into the flask from where it flowed through a pipe to the collection flask. The molar volume of H2 gas at room temperature is 22.79 l/mol, which is also the rate for the hydrogen gas in the collection flask. The amount of H2 gas in the flask is impossible to calculate for the amount of water vapour and air was measured when performing the experiment. The experimental value turned out unexpectably very small. 0.36% error in the experiment seems very small, unless there has been some unnoticed mistakes that have influenced the experimental value.

The theoretical value is 22.5 l/mol.

Temperature changes during the experiment turned out some interesting results, for the temperature seems to start falling soon after the chemical reaction has ended, yet it begins to rise a little after a few minutes and stays constant for a long time before starting to fall (figure 3.2). From the information gained during this experiment, it is difficult to state why this happened; therefore, some extra research should take place if performing the experiment again.

Improved investigation: For further investigation, temperature should be measured for longer than 15 minutes in order to find out the rate the temperature is going to fall in a closed flask. The distance between water surface in the container and the surface in the flask should also be measured. For more accurate results, factors such as air and water vapour in the flask should be taken into consideration when calculating the final values. Advisable would be to do some research on why the temperature changed the way it did in this experiment.

An experiment to obtain Zinc Oxide from Calamine Essay

An experiment to obtain Zinc Oxide from Calamine Essay

This will be repeated until the weight of the test tube with its contents is identical. E. g. 1st reading= 17. 24g, 2nd reading= 17. 18g, 3rd reading=17. 15g, 4th reading=17. 15g The underlined readings are identical; consequently I would stop and record these readings. I would do it like this because when the readings are the same it means that the reaction has stopped and there is no need to go any further. This is done for every amount. Fair Test There are many things that can be done to keep this experiment a fair one.

Firstly the same test tube must be used as all of them have different weights.

The amount of time you leave the test tube on the Bunsen burner is also crucial, as it would not be a fair test if you left one test tube in the heat longer than the others. You must measure the amount of mineral wool you put in the test tube so that you can deduct that and the weight of the test tube to get your result.

Errors will be kept to a minimum with the use of digital weighing equipment. Preliminary work My preliminary work consists of an experiment titled ‘Obtaining Copper Oxide from Malachite’. Malachite is a mineral that contains copper. In the experiment we heated the Malachite in an attempt to obtain Copper Oxide.

From the experiment I acknowledged that as the mass of Malachite increased so did the mass of Copper Oxide. The experiment was extremely similar to this experiment, thus I would expect the same to happen in this case. Therefore, in this experiment, the more Calamine that is used the more Zinc Oxide that will be produced. It doesn’t take a genius to work that out though. -7- Jack Mariner Chemistry Coursework Results: Chart 1 Reading Amount of Calamine (g) Amount of Zinc Oxide produced (g).

Shown above are the results from the experiment and below is a graph plotted from these results. -8- Jack Mariner Chemistry Coursework Graph 1 is a bar chart showing the amount of Calamine used, plotted against the amount of Zinc Oxide produced. Although this graph may look pretty, it is not very useful. From just using these results, it is difficult to explain and understand the graph, so something else is needed: The theoretical amounts. Chart 2. No. of readings Amount of Calamine (g) Theoretical amount of ZnO Predicted (g) Actual amount of ZnO Produced (g).

These theoretical amounts have already been calculated. To add these to the graph like on the next page will help us to analyse the results in more detail. -9- Jack Mariner Chemistry Coursework Now this graph is worth looking at. It shows the theoretical amounts of Zinc Oxide produced, plotted against the actual amount of Zinc Oxide produced. So theoretically, in perfect conditions, with a perfectly fair test in practise, the theoretical results would be achieved. My experiment however wasn’t done in these conditions, which is why the results do not resemble each other perfectly.

-10- Jack Mariner Chemistry Coursework Graph 3 is a line graph, which I feel shows the information more clearly. From it you can see that the theoretical amounts are similar to the actual amounts of Zinc Oxide produced, however there is room for a lot of improvement. For instance, reading 2. This was done using 1. 5g of Calamine. Something definitely went wrong here because it is so out of proportion to the other results. Due to the obvious mistake I took the liberty of requesting a glimpse of another group’s results, to compare with mine and to see their result for 1. 5g of Calamine. Chart 3 Reading Amount of Calamine (g).

Actual amount of ZnO Produced (g) Other Group Comparison of ZnO Produced (g) From Chart 3, you can see that my results are in fact relatively similar to the other group’s results that I have compared with. The reasons for the differences are probably due to spillages or how concentrated the substances were, etc. Analysing the Results To analyse my results I shall look back at them individually. ‘Chart 1’ shows only my results. These were very pleasing because they were nearly as I predicted.

At this stage I wasn’t aware of any anomalous results as the relationship between them looked good. I am still satisfied with my results but would like to redo the test for 1. 5g of Zinc Carbonate. This would give better results to analyse and to draw a conclusion from. The second chart, ‘Chart 2’, showed the theoretical amounts. I included these into my experiment so that I could see how accurate my results were. Comparing with another group is good, but their results could also be wrong. Comparing with these theoretical results would show me immediately the accuracy of my results.

I have drawn the graph on the next page to demonstrate this. -11- Jack Mariner Chemistry Coursework So the graph is really a way of measuring your accuracy. To do this I worked out the percentage (%) yield. This was done by using the equation; % yield = actual amount theoretical amount From the graph you can see that the majority of my results were very accurate. I have done readings 2 and 4 in a different colour because they are obviously wrong. They both have a percentage yield of over 100%, which is impossible. The reason for this is probably due to contamination and impure Calamine. These two readings are therefore anomalous results.

‘Chart 3’ shows that my results are actually fairly similar to those from the other group. Apart from the obvious experiment error in reading 2, the thing that catches my attention most is the fact that my results are all higher than those from the other group. This could be resulted from a number of things, for example the use of different pieces of equipment, or the stopwatch counted seconds at slightly different rates, consequently that group leaving the test tube under the heat for a longer period of time. Or on the other hand these results maybe higher then the compared groups results as a complete coincidence.

-12- Jack Mariner Chemistry Coursework Conclusion From ‘graph 3’, you can see that my hypothesis is of high quality stating that I predicted a graph with strong positive correlation. This was almost a perfect prediction. My conclusion really for this experiment is that as the amount of Calamine increases so does the amount of Zinc Oxide produced from this. Theoretically this is done proportionately, but actually anomalous results interfere, leaving the results strongly related with strong correlation as apposed to a theoretical graph with perfect correlation.

Evaluation I consider this experiment to be a success. The plan was followed very well and the results were of good quality. The measurements were done accurately, and a fair test was achieved. The procedure used was also a very fair and efficient one. Although the experiment was a success, I am still bothered by the fact that anomalous results occured in my experiment. I think that the reasons for these results were because of time limitations. We had very little time to accomplish this task successfully, so mistakes were inevitable.

The improvements, which could be made in doing this experiment, are to have a longer time to do the experiment so that isn’t done making careless mistake and if mistakes were made, there would be enough time to redo what was needed. Secondly more high tech equipment could be used to get more reliable and accurate results. Also, an essential thing is for the Calamine used to be pure. This is important because impure calamine could react at a different rate to more pure Calamine. This would have a huge bearing on the final result. Lastly, more readings could have been taken. This would lead to averages being taken giving better results.