Text 2 Rates of reactions science - Queen Mary University ... GSCE Chemistry... · Main experiment...

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Contents page:

Introduction to rates of reactions 3-5

Preliminary test introduction 6

Preliminary test 1 6-12

Preliminary test 2 13-14

Main experiment 15-17

Main experiment results 17-19

Main experiment Conclusion 19-21

Main experiment evaluation 21-22

Bibliography 23

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Rates of reactions science (chemistry) coursework

My coursework is based on rates of reaction. This deals with the time taken for

reactants to be changed into products, when the variables are altered and analysed.

Rates of reaction deals with the collision theory, this theory explains how frequently

and how hard (sufficient energy) the reacting particles collide with each other (old

bonds break and form new bonds). I will be aiming to get the most accurate and

reliable results; therefore I repeated all of my experiment several times to make it a

fair test. Since I had a limited amount of time I chose to do the precipitation formation

method for my trial run and for my final experiment I chose to do the volume of gas

given off experiment. My main aim is to see if the combination of different chemicals

and the volume of different chemicals affected the rates of reactions occurring.

Rates of reaction deals with the collision theory, this theory explains how frequently

and how hard (sufficient energy) the reacting particles collide with each other (old

bonds break and form new bonds).

I was given four different methods to measure the rates of reactions for my trials and

final experiments.

The four different ways to measure rates of reactions are:

1. Precipitation formation is when you draw a cross on a piece of paper, then

placing a conical flask on top of the cross. After that you put the solution

inside the flask and the product of the reaction should produce

precipitation/clouds in the solution the person who observes the cross should

measure how long it takes the cross to disappear, this is subjective it will only

work if the initial solution in clear.

Mixture reactions taking place stop the clock

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2. Change in mass (usually gas given off) is when the solutions reading decreases

at a rapid rate, the faster the reaction is the more gas is produced. It is easier to

plot the rate of reactions on graphs, if the reaction produces gas you should

measure the speed of gas being produced.

3. Volume of gas given off is the most accurate of the three methods (mass

balance involved). This method is when you put the reactants in a conical

flask, placing a gas syringe on top of the conical flask, and measure the

volume of gas given off; the volumes are accurate to the nearest cm3. It is a

good idea to stir the solution for better reaction.

5

4. Time taken for solid to disappear. this is when a solid form of sodium

thiosulphate is put into hydrochloric acid and the time is measured to see how

long it takes for the sodium thiosulphate to disappear, there are different

compounds to dissolve such as marble chips, powdered marble chips, sodium

thiosulphate and calcium carbonate, to use this method you can change the

amount of compound put in to the conical flask or the volume of hydrochloric

acid, this is a good method to try surface area for rates of reactions.

6

My preliminary tests

I believe that preliminary tests are every important because it gives me an idea of how

to carry out the final experiments, it also gives me a chance to identify any anomalies

and correct my mistakes so I have a more accurate and reliable result in my final

experiments. There are many variables which could have an affect on the outcomes of

experiments such as:

• the temperature, if the temperature changes in the room then the results will

vary to overcome this, all the experiments will be done at room temperature

and kept a far distance away from light bulbs because light bulb will change

the results even if it is by a fraction,

• if the wind blows towards the solutions it will change the temperature or it can

affect the speed of the reaction if I was to use a Bunsen burner it might blow

the flame out and the test will have to be repeated,

• The concentration of the reactants will have an affect because if it isn’t mixed

or measured accurately the reactions will happen at a different rate.

Each experiment will be tested in the same area so all the factors that can affect the

outcome of my results can be controlled, for example to control the temperature; I

kept all windows closed throughout each test controlling the room temperature, the

advantage of testing all the variables in the same place is that if there is a problem in

that area for the variables it can be fixed and that area will become the most suitable

place to carry out any experiments.

Preliminary test 1:

Aim: To see if measuring the time taken for a solution to precipitate will help make

an accurate and reliable result for rates of reactions. I aim to change the

concentration of sodium thiosulphate and react it with hydrochloric acid and see

how quickly the solution precipitates.

Equipment list

• Conical flask – 1

The reason why I chose a conical flask is because it is easy to put the reactants in to it,

the conical flask keeps spillage to a minimal and any extra fizzing of the solution will

be stopped from coming out because of the way the top closes in,

• Beaker – 2

I chose two beakers because it can hold in the sodium thiosulphate and the

hydrochloric acid that I am using separately and it is easier to pour the reactants out,

• Small beaker – 1

I used a small beaker because I am using a little bit of water and the small beaker will

help save space so the equipment can be set up,

• Pipette – 3

I used three pipettes because I have three fluids which are sodium thiosulphate,

hydrochloric acid and water plus I don’t want to cause any reactions so I put 1 pipette

in each beaker also the pipettes are very accurate to measure with,

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• 25ml measuring cylinder – 2

I used a two 25ml measuring cylinder because it measures the fluids accurately and

the maximum amount of concentrations we were using was 20ml so it was suitable for

the experiments,

• Small 20ml measuring cylinder – 1

I used a small 20ml measuring cylinder because again I was only using a small

amount of water and the measuring cylinder will make the pouring of the reactants

accurate,

• Cotton wool – big bunch

I used a big bunch of cotton wool so that I can cover the top of the conical flask so

any part of the solution fizzing will be kept inside the conical flask which will stop

anything from corroding,

• 200ml hydrochloric acid- (reactant I was given) so I don’t have to keep

refilling the beaker

• 200ml Sodium thiosulphate- (reactant I was given) so I don’t have to keep

refilling the beaker

• 25ml water- to keep the reactants stable,

• Digital stopwatch

I used a digital stopwatch because it is accurate to the nearest 100th of a second and a

analogue clock will only measure the time to the nearest second.

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Method:

1. draw an x on a piece of paper and pour 200ml of sodium thiosulphate and

hydrochloric acid in different beakers,

2. pour 25ml of water in a small beaker,

3. get a conical flask and put it on top of the x,

4. pour 20ml of sodium thiosulphate and 5ml of hydrochloric acid into a 25ml

measuring cylinder (in two separate cylinders and also use pipettes because

they measure accurately) and then pour both into a conical flask after that

immediately cover the top of the flask with cotton and start the timer,

5. the person who is looking at the solution should be the timer,

6. when the reaction has finished, stop the clock and record the time in a table

7. repeat each step but go down by 20% concentration, keep the acid same and

add 1ml of water after the first run each time,

8. after doing step 7 another 4 times draw another table and do the trials again

starting from step 1 do this however many times possible to get the best

possible results.

The variables that I need to control is the concentration of hydrochloric acid, total

volume of sodium thiosulphate, type of acid, temperature of water, the equipment

type, my method for each trial repeat and I will keep all other variables not caused by

me constant, like room temperature, by keeping windows closed and everything else

to be around about room temperature here is a diagram showing how to set up every

equipment:

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Results for preliminary test 1, repeats 1,2,3

0

20

40

60

80

100

120

140

160

0 20 40 60 80 100 120

concentration of sodium thiosulphate (%)

time taken for "x" to disappear (s)

Series1

Series2

Series3

Best estimates for my 3 preliminary repeats:

Average result for 100% concentration = 26.48





Concentration

of sodium

thiosulphate

(ml)

Volume of

water

(ml)

Volume of

hydrochloric

acid

(ml)

Time taken for

“x” to

disappear,

Repeat 1

(s)

Time taken for

“x” to

disappear,

Repeat 2

(s)

Time taken for

“x” to

disappear,

Repeat 3

(s)

20 (100%) 0 5 26.01 26.84 26.58

16 (80%) 4 5 30.41 34.41 35.12

12 (60%) 8 5 35.42 37.67 38.94

8 (40%) 12 5 69.91 68.52 70.05

4 (20%) 16 5 145.43 143.34 143.08

Repeat 1

Repeat 2

Repeat 3

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Average results for preliminary test 1,

26.4833.31

69.49

143.98

37.34

0

20

40

60

80

100

120

140

160

0 20 40 60 80 100 120


time taken fo "x" to disappear (s)

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Analysis of trial run:

During the first trial run I changed the volume of sodium thiosulphate in ml and water

also in ml. I chose to measure in ml because the concentrations of the fluids are best

in small volumes, I found this out as I used large numbers for another test, and the

results had varied significantly. I changed the concentration of sodium thiosulphate

and water to get a better result and to see if the results have a correlation, to see if the

concentration of sodium thiosulphate and water affects the time. I noticed that when

the reactants concentration was low the more time it took to precipitate, the changes I

will make in the second trial repeat will be minor, for instance:

• I will check that no human errors will occur by checking that the concentration

of the reactants will be precise

• the temperature for the room will stay constant and also for the second trial

repeat

• I will try to do all the experiments quickly so if the temperature of the room

changes every half hour it would not make a significant difference because I

would have finished the trials before,

• I will not rush the trials too much because I do not want to affect the results.

I chose the precipitation formation as a trial run because it seemed to be the most

accurate, also because the other experiments seemed very complex and human errors

would be more likely during the experiments, say for instance the time taken for solid

to disappear I would have had to measure the compounds on a scale and if I

accidentally put too much I would have to take some off but, while I am doing that the

scales will get unbalance because of the change in weight and the scales might say 2

grams but it is actually 1.86 grams, the 0.14 grams difference might be a massive

impact on the result. I think the test I had done was fair because I tried my best to get

the concentration correct but for the second trial I will do a better job because I now

have some practise and for the second trial I should be able to set up the equipment

quicker and record the results for the trial better. I will keep my method the same

because it will allow me to get a more accurate mean result, I will keep the variables

same which is concentration to test in the trial run.

In the second trial repeat I did not see a huge difference in results, the results had

changed by a fraction in seconds and the same incident happened during the third trial

run the results not change hugely, but nevertheless doing three trial runs will insure

the fact that I will get a accurate and reliable result which I will be able to analyse in a

descriptive manner.

The concentration of the hydrochloric acid that I am using is 2mM and the

concentration of the sodium thiosulphate is 0.20, so the ratio for hydrochloric acid to

sodium thiosulphate is 8:1; this was another reason why I had to use small doses of

hydrochloric acid so I can make the concentration fair. We did not do any tests to find

out how much hydrochloric acid to use we just kept the hydrochloric acid

measurement invariable, and we changed the quantity of sodium thiosulphate and

water.

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Evaluation of trial run:

The correlation I saw in the graph I created was that as the concentration percentage

had increased, the time taken for the solution to precipitate had decreased. The ranges

for the results weren’t that big they were only a few seconds apart and the ranges did

not overlap which was proof that concentration affected rate of reaction by speeding

up reactions and causing precipitation. The ratio for hydrochloric acid, water and

sodium thiosulphate is 0:1:4 because the reactants will go up by the ratio 0:1:4 each

test. After I had finished all my trial runs I have decided that the disappearing ‘x’

method is not accurate enough because I have ended up with an outlier but the results

did prove that concentration does effect the rate of reactions, I think that there is an

outlier because of human errors the concentration was not measured properly or

because of the fact that the person timing was not able to stop the digital stopwatch on

time, I noticed an outlier when I had done a graph on the computer and the curve of

best fit did not look correct it ended up looking like this:

Wrong ��

I had drawn a graph on computer to get accurate results I also did not want to take the

risk of making an inaccurate graph and it paid of because it had shown the outlier I

didn’t notice, I have decided that for my second preliminary test experiment I will do

the volume of gas given off method because the gas will be measured easier, also for

my second preliminary experiment I will give a certain amount of time for the gas to

be produced, and in the graphs and tables I will record the gas given off and the

concentration, the concentration will go down by 25% each time because I have been

given a limited amount of time to carry out the second trial run and 4 tests should be

enough, also if I had done another percentage such as 30% the ratio of hydrochloric

acid and calcium carbonate will be corrupt.

Preliminary Test 1-3: Time Taken for 'x' to disappear

(Rates of Reaction)

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

110.00

120.00

130.00

140.00

150.00

160.00

0 20 40 60 80 100 120

Concentration (%)

Time Taken (seconds)

13

Preliminary test 2:

Aim: to see if measuring the volume of gas given off will help me with my main

experiment.

Equipment:

• 1 Conical flask

• 2 beakers

• 1 pipette

• 1 gas syringe

• Calcium carbonate- I chose calcium carbonate because sodium thiosulphate

might not react quickly enough for me to record the volume of gas.

• Hydrochloric acid

• Weighing scale- accurately weighs the pellets,

• Digital stopwatch

Method:

1. wear goggles, find a safe distance away from the equipment to avoid reactants

spilling on me, set up equipment,

2. use the weighing scales to measure 2g of calcium carbonate, and use the

pipette to pour 5ml of hydrochloric acid,

3. put both the reactants in the conical flask,

4. immediately start the timer and wait for 1 minute the record the gas given off,

5. do steps 1-4 another three times and each time the calcium carbonate should

go down by 0.5g and the hydrochloric acid should stay the same,

6. After doing step 1-4 another three times, draw an extra column and repeat step

5 another 2 times.

Time given

for gas to be

produced

(minute)

PH

level

Volume of

hydrochloric

acid (ml)

Concentration

of calcium

carbonate (g)

Volume of

gas produced

repeat 1

(cm3)

Volume of

gas produced

repeat 2

(cm3)

Volume of

gas produced

repeat 3

(cm3)

1 Ph2 5 2(100%) 150 148 149

1 Ph2 5 1.5 (75%) 130 142 140

1 Ph2 5 1 (50%) 122 125 130

1 Ph2 5 0.5 (25%) 115 120 127

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Evaluation of trial 2:

The table shows that the higher the concentration of calcium carbonate the more gas is

produced. The results were fairly accurate and I could use this method for my main

experiment but in the main experiment I will change the calcium carbonate to sodium

thiosulphate and to speed up the reaction I will use a Bunsen burner. Also in my main

experiment I will be going up by 10% concentration of sodium thiosulphate each time

so I have more results to make better conclusions.

Average volume of gas given off, preliminry test 2,

149

137

126121

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

0 25 50 75 100 125

concentration of calcium carbonate (%)

volume of gas produced (cm3)

results for preliminary test 2, repeats 1,2,3

130

122115

142

130127

150148

125120

149140

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

0 25 50 75 100 125

concentration of sodium thiosulphate

gas produced (cm3)

Series1

Series2

Series3

Repeat 1

Repeat 2

Repeat 3

15

Main Experiment:

Aim: To see if measuring the volume of gas given off will help to write up a

sensible evaluation on the rate of reactions.

Prediction: my prediction is that the volume of gas will be accurate,

The gas produced will be a large number, and there will

Be no flaws also the method will help with my evaluation.

Fair testing:

During the main experiment I had given the reactants 1 minute to react with each

other so the results can be fair and instead I measured the volume of gas given off, I

cleaned the equipment before the next test so the solution left over will not affect the

reactants for the next test, I left the equipment to dry so the water used to clean the

equipment will not affect the reactants, I had done the main experiment within 1 day

so the because the temperature on the following day may cause non-reliable results, I

did not use a catalyst, I did not change the type of acid, I kept the temperature of the

water constant so reactants will be stable, I kept the person reading the temperature

the same because different people may see different results, I did not change the

position of each equipment, I used the same bunsen burner because other bunsen

burners might heat chemicals faster. For my results to be accurate I left the equipment

at the same height level because if the gas syringe was slightly lower or higher it

might be harder for the gas to get to the gas syringe, I repeated the experiments, I used

a pipette because it is accurate to the nearest drop and I used a digital stop clock

because it is accurate to the nearest millisecond.

Method:

1. Gather all the reactants and set up the equipment so all the reactants can be

poured in easily and so all the equipments that need to be washed can be easily

detached and attached back quick and with no hassle,

2. use a pipette to squirt in 20ml of sodium thiosulphate in one measuring

cylinder, and do not use any hydrochloric acid,

3. pour the sodium thiosulphate in to a conical flask,

4. immediately afterwards switch the Bunsen burner on so the reaction can take

place quicker,

5. exactly as the digital stopwatch goes on 1 minute switch off the Bunsen burner

and allow the reactants to cool down for 1 minute,

6. Record the volume of gas given off, the ph level and record the temperature

after 1 minute to see how quick the solution heats up and how hot it is after 1

minute,

7. repeat steps 1-6 for another 9 times but each time the volume of sodium

thiosulphate should go down by 2ml and the volume of hydrochloric acid

should stay 5ml, record the results each time, also remember to clean the

conical flask so previous reactions will not affect the result of the next repeat,

8. After repeating step seven 9 times, draw another table and start from step 1, do

this however many times possible to get reliable results.

16

I have changed my main experiment method from my trial runs method, just the

first few steps but the last two I have kept the method the same because repeating

the methods will give the best results needed to write up a good evaluation so I

can explain if concentration does affect rates of reactions. All the other variables

will be kept constant by not changing the position of the equipment and keeping

the factors which will affect my results in a stable condition or if there were any

factors in the first experiment which changed the results I will redo the experiment

again so I can get precise results e.g. if the temperature suddenly changed I will

change the temperature back by doing whatever is necessary and redoing the

experiment that had been affected by the temperature.

Here is a diagram showing how the equipment should be set up:

Equipment list:

Conical flask – 1

Bunsen burner – 1

Beaker – 2

25ml measuring cylinder – 2

Goggles – 3

Tripod - 1

Stands – 2

Heat proof mats – 1

Clamps – 2

Gauze – 1

Pipettes - 2

Thermometer – 1

Gas syringe – 1

Universal indicator

Hydrochloric acid 2mW (200ml)

Sodium thiosulphate 0.20mW (200ml)

17

The reason I chose to use a gas syringe is because it measures accurately to the

nearest cm³, I chose 2 stands and 2 clamps so I can keep the gas syringe and the

conical flask in position during the experiment, I used a gauze to protect the conical

flask from burning, I used a heat proof mat to prevent any objects near the bunsen

burner from burning and to prevent the work surface from corrosion, I used a tripod to

keep the conical flask at least 5cm away from the bunsen burner so the conical flask

won’t heat up rapidly, I used goggles to protect myself from any fizzing as well as

burning and rubber bung along with rubber tubing to connect the conical flask to the

gas syringe firmly and tightly.

Results for my main experiment:

The time I gave for the gas to be produced was 1 minute.

Concentration

of sodium

thiosulphate

(ml)

Volume

of

water

(ml)

Volume of

hydrochloric

acid

(ml)

Volume

of gas

produced

Repeat 1

(cm³)

Volume

of gas

produced

Repeat 2

(cm³)

Volume

of gas

produced

Repeat 3

(cm³)

Volume

of gas

produced

outlier

repeats

(cm³)

Average

volume

of gas

produced

Average

temperature

after 1

minute to

cool down

( C)

20 (100%) 0 5 52 50 53 51.6

59

18 (90%) 2 5 47 49 48 48 61

16 (80%) 4 5 45 47 44 43 44 64

14 (70%) 6 5 40 43 41 42 41.3

66

12 (60%) 8 5 35 36 34 35 69

10 (50%) 10 5 26 29 27 27.3

72

8 (40%) 12 5 25 22 24 23.67

73

6 (30%) 14 5 23 20 22 21 21.67

75

4 (20%) 16 5 20 17 18 18.3

78

2 (10%) 18 5 16 14 17 15 15.67

80

18

Results for main experiment repeats 1,2,3

0

5

10

15

20

25

30

35

40

45

50

55

60

0 10 20 30 40 50 60 70 80 90 100 110

Concentration of sodium thiosulphate (%)

Volume of gas given off (cm3)

Series1

Series2

Series3

Repeat 1

Repeat 2

Repeat 3

rate graph for my main experiment

1.838

2.2082.421

2.857

3.663

4.225

4.615

5.465

6.382

2.083

0

1

2

3

4

5

6

7

0 10 20 30 40 50 60 70 80 90 100 110


Rate (to the nearest 1000th of a decim

al)

19

Conclusion:

The formula for the reaction was HCL + Na S O � NaCL + H O + H + S + SO, the

gas produced in the reaction was hydrogen and probably trace amounts of sulphur

dioxide because there was a limited supply of oxygen. To conclude the general trend I

saw on the graphs was that as concentration increases the gas produced increases I

think this is because, of the volume of fluids I had used, I think the fact that I changed

the concentration of sodium thiosulphate made the reactions occur at a faster rate

because in the results I had noticed that the volume of sodium thiosulphate affected

how much gas was produced like when I used 100 % concentration of sodium

thiosulphate the hydrochloric acid was 5ml and that’s when the most gas had been

produced, the gas produced was 53cm3 of hydrogen in repeat 3 of the main

experiment, the volume of gas was quite high and I did predict that the volume of gas

will be high and accurate so I am satisfied with the results I had recorded, the

collision theory does show that if the concentration of one reactant increases the

number of successful collisions increases. The scatter on my graph is close to the line

of best fit which means that the results recorded were accurate and there were almost

no flaws at all, the scatter does show that as concentration increases the volume of gas

increases, like at 10% concentration the volume of gas was 15.67cm3 and at 60%

concentration the volume of gas is double that which is 35, the reason I think there

were almost no flaws is because there are 2 results which are slightly more further

away than the other results but that could be a result of inaccurate reading of the

result. There is a random leap for the volume of gas produce between 50% and 60%

concentration that is probably because the volumes of water, hydrochloric acid and

sodium thiosulphate were most stable at 60% concentration causing the reactions to

take place quicker also producing more gas, and after 60% concentration the volume

of gas produced increases significantly in addition the gradient of that part also shows

that the results were steeper. The error bars are small which shows that my results are

average voulme of gas produced for main experiment

51.6

48

44

41.3

35

27.3

23.6721.67

18.3

15.67

0

5

10

15

20

25

30

35

40

45

50

55

60

0 10 20 30 40 50 60 70 80 90 100 110


average volume of gas (cm3)

Series1

Series2

Series3

Highest value

Average

Lowest value

The average gradient for this part

of the graph is 0.941, this is

because the reactants are partially

stable but the reactants did still

react quickly.

The average gradient for this part of

the graph is 0.558, this is because the

reactants are more concentrated and

stable, and the reactants are also

reacting at a rapid rate that’s why it is

steeper on this part of the graph.

20

reliable because the results only varied by a fraction meaning that all my experiments

were carried out fairly like keeping variables not caused by me constant.

The rate of reactions depends on how many successful collisions there are between

the reactants as reactions happen at different rates depending on the variables. The

higher the number of successful collisions, the faster the rate of reactions.

For a reaction to take place the reactants must produce enough energy to collide, this

is called activation energy. To increase the success rate of collisions you should

increase:

• the temperature which will make the particles move around quicker, and give

it more energy,

• Changing the concentration or pressure which will make the particles more

crowded resulting in more collisions,

I had changed the concentration in my main experiment, and the results I found did

show that as the concentration of sodium thiosulphate affected the number of

successful collisions I think this is because there are so many particles and the number

of collisions kept on occurring because the particles were densely packed which

resulted in enough energy in the collision to cause the reactants to merge and become

a different product this is what activation energy is. Activation energy is when the

energy produced in a collision is at its peak point and the reactants are forced to fuse

together.

• Grinding the particles down will allow the particles cover a larger surface area

21

• Adding a catalyst substance like iron, platinum or vanadium (V) oxide will

speed up the reactions.

To get a concrete conclusion I will have to do the experiments again and record better

results but this time I will know what to improve on such as which concentrations to

use and which reactant should be the variable, and I will have a chance to try out the

temperature part of the collision theory by using water bath and leaving the reactant

there for about 2 minutes and see what is produced.

Evaluation:

The results I have collected are fairly good, there were a few results which were

outliers in experiment repeat 2 of my main experiment but because the results were

repeated so the average will not be affected, the outliers might have been a human

error I might have counted the result wrong, the outlier does not affect the average on

a huge scale I still got a very good line of best fit. The ranges for each repeat were

small enough to make a reliable graph except I don’t think that the results are accurate

enough for solid evidence to prove that concentration affects rates of reaction.

I think that if I had recorded the results accurately in addition to knowing which

concentration to increase I would have had a better result, next time I would try to do

a better job in the experiments because I believe that the method was fine and how I

carried out the task was fine but the little anomalies which appeared like the big gap

between 50%-60% concentration were because of the mistakes I had created, I could

have read the gas syringe wrong and next time I will use computerised data logging

system to record my data so the data is accurate and I will also try to find a gas

syringe which measures to the nearest 100th of a cm. The apparatuses and my method

did not affect my results because everything was put in a position and not moved and

the main equipment such as the conical flask was cleaned so the solution created

before will not affect the reactants used in the next experiment. To get more accurate

results I could have used a burette but due to limited amount of equipment I was not

able to, also I could have spent more time on each experiment but due to limited

amount of time it was not possible because if I did take time doing tests repeats would

be missing and the results will be less accurate.

My conclusion is reliable and shows that concentration affects rate of reactions, but

mistakes were made during the experiments because during repeat 2 of my main

experiment I did get 4 outliers probably because the result was not read properly or

the timer was not stopped exactly at 1 minute, nevertheless I redid them to get reliable

results. Next time to improve on my method by using a computer data logger, I will

find a as cylinder which measures to the nearest 100th of a decimal, instead of using

heat I would use a catalyst to speed up reactions and I will use a burette because it is

easier to use and less likely to contribute to human errors it also measures to the

22

nearest drop. There is evidence to prove that concentration affects rates of reactions

like when the concentration was high the number of successful reactions occurring

where large I think this is because of the fact that the volume of sodium thiosulphate

was high and the hydrochloric acid was low, so the collisions just kept on occurring

on top of that science does back my results up because collision theory clearly states

that when the concentration of the reactants increases the number of successful

collisions increases. My study was large enough investigation to get accurate data, if I

had been able to do all 4 methods and all four factors I would have been able to

compare results and see which factors affect rates of reactions more and how they

affect it which will give me better results. I could have collected another pupils data to

compare my results to because the other pupils may have slightly done the method

different or another method overall.

By Layak Khan

23

Bibliography:

Wednesday February 2

nd 2011

Research from:

http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway/rocks_metals/7_faste

r_slower5.shtml


r_slower4.shtml


r_slower3.shtml


r_slower2.shtml


r_slower1.shtml

Picture from:

http://www.google.co.uk/search?q=collision+theory&ie=utf-8&oe=utf-

8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

http://www.google.co.uk/images?um=1&hl=en&safe=off&client=firefox-

a&rls=org.mozilla%3Aen-

US%3Aofficial&biw=1280&bih=841&tbs=isch%3A1&sa=1&q=collision+theory+-

percipitation+formation&aq=f&aqi=&aql=&oq=

http://www.google.co.uk/images?um=1&hl=en&safe=off&client=firefox-

a&rls=org.mozilla%3Aen-

US%3Aofficial&biw=1280&bih=841&tbs=isch%3A1&sa=1&q=rates+of+reactions+

-precipitation+formation&aq=f&aqi=&aql=&oq=

Thursday February 10th 2011:

Research and pictures from:

http://www.docbrown.info/

http://www.docbrown.info/page03/3_31rates.htm

Text 2 Rates of reactions science - Queen Mary University ... GSCE Chemistry... · Main experiment...

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