C2 4.1a – Student practical sheet
Measuring the rate of reaction 1: volume of
gas
Reactions that produce a gas may be followed by measuring the volume of gas produced using a
gas syringe.
Aim
To follow the rate of the reaction between marble chips (calcium carbonate) and hydrochloric acid
by measuring the volume of carbon dioxide produced over time.
Equipment
●
eye protection
●
conical flask
●
bung/delivery tube/gas syringe
●
marble chips
●
hydrochloric acid
●
stopclock or stopwatch
●
graph paper
Safety
●
Wear your eye protection.
●
Wash your hands after handling the marble chips and acid.
What you need to do
1
Collect the equipment and clamp the syringe horizontally.
2
Attach the delivery tube and bung and position it so that the bung can be quickly fitted to the
flask.
3
Pour 50 cm of dilute hydrochloric acid into the flask.
4
Add a few marble chips, push in the bung and start the stopclock.
5
Note the reading on the syringe every 15 seconds, recording these results in a suitable table.
3
Using the evidence
1
Plot a graph of your results, with time along the x-axis and the total volume of gas along the yaxis. (5 marks)
Evaluation
2
Comment on the shape of your graph. When did the reaction finish and how do you know?
(4 marks)
Extension
3
Did the slope of your graph change during the experiment (before the reaction stopped)? If so
comment on this change and suggest a reason for it. (3 marks)
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209
C2 4.1b – Student practical sheet
Measuring the rate of reaction 2: mass of gas
Marble chips contain calcium carbonate. They react with hydrochloric acid to form calcium chloride,
water and carbon dioxide. As carbon dioxide is a gas, it leaves the reaction and goes into the air.
This makes the container in which the reaction is taking place lose mass.
Aim
To follow the rate of the reaction between marble chips (calcium carbonate) and hydrochloric acid
by measuring the mass of carbon dioxide produced and ‘lost’ over time.
Equipment
●
eye protection
●
250 cm conical flask
●
cotton wool
●
hydrochloric acid
●
marble chips
●
50 cm measuring cylinder
●
piece of paper
●
top-pan balance
●
clock
3
3
Safety
●
Wear your eye protection.
●
Wash your hands after handling the marble chips and acid.
What you need to do
3
1
Using the measuring cylinder, put 50 cm of hydrochloric acid into the conical flask.
2
Place a loose plug of cotton wool in the neck of the flask.
3
Weigh out 20 g of marble chips onto a folded piece of paper.
4
Put the flask and the paper on the pan of a balance.
5
Press the tare button on the balance, so that all of the apparatus weighs zero.
6
Remove the cotton wool and add the marble to the acid. At the same time start the clock.
7
Replace the cotton wool in the neck of the flask. Put the flask and paper back onto the balance.
8
Read off the mass of the apparatus every 30 seconds until the reaction stops.
9
Copy and complete this table. Calculate the loss of mass for each time by removing the minus
sign from the balance reading.
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C2 4.1b – Student practical sheet
Time (minutes)
Reading on balance (g)
0
0
Loss of mass (g)
Using the evidence
1
Plot a graph of your results, with time (minutes) along the x-axis and the total mass of carbon
dioxide lost (g) the y-axis. (6 marks)
2
Why has the apparatus lost mass? (2 marks)
3
There were some marble chips left at the end of the experiment. Why did the reaction stop
before these chips had reacted? (1 marks)
4
Look at your graph. How can you tell from your graph that the reaction has finished? (1 marks)
5
How long did it take for the reaction to finish? (1 marks)
6
Calculate the average rate of reaction (in terms of mass of carbon dioxide produced per
minute) for the first 2 minutes. (2 marks)
7
Write a word equation for the reaction between calcium carbonate and hydrochloric acid.
(3 marks)
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211
C2 4.1c – Student worksheet
Measuring reaction rates
A student carried out the experiment shown, measuring how much gas was given off every
10 seconds.
Time
Volume of gas
(s)
(cm3)
0
0
10
15
20
26
30
34
40
40
50
45
60
48
70
50
80
50
90
50
1
Plot a line graph of the results. (2 marks)
2
How much gas was given off after:
3
a
12 seconds? (1 mark)
b
26 seconds? (1 mark)
c
55 seconds? (1 mark)
a
When was the reaction over? (1 mark)
b
How can you tell? (1 mark)
c
What was the total volume of gas made at the end of the reaction? (1 mark)
4
What happens to the rate of reaction as time goes by? (1 mark)
5
Explain why you think this change of rate occurs. (1 mark)
6
The rate of this reaction can be measured as the volume of gas given off per second. What is
the rate of the reaction:
7
a
during the first 10 seconds? (2 marks)
b
between 40 and 50 seconds? (2 marks)
Comment on the experimental method used. How does this method compare to the ‘gas
syringe’ method, in terms of ease of use and accuracy? (2 marks)
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C2 4.2a – Student practical sheet
Temperature and the ‘disappearing cross’
reaction
You are going to investigate the reaction between sodium thiosulfate and hydrochloric acid. The
two chemicals react to make sulfur, which is a solid. This makes the solution go cloudy. You can
measure the rate of reaction by timing how long it takes for the solution to become cloudy.
Sodium thiosulfate + hydrochloric acid → sodium chloride + sulfur dioxide + sulfur + water
Aim
To investigate the effect of temperature on the rate of reaction in the ‘disappearing cross’
experiment.
Equipment
●
eye protection
●
sodium thiosulfate solution
●
conical flask
●
dilute hydrochloric acid
●
scrap piece of paper (to draw a
cross on)
●
50 cm measuring cylinder
●
stopclock or stopwatch
●
10 cm measuring cylinder
●
thermometer
●
water baths/ice baths
3
3
Safety
●
Wear your eye protection.
●
Sulfur dioxide is toxic and corrosive. Do not inhale any fumes and tell your teacher if you have
asthma. Dispose of the solution immediately after the experiment following your teacher's
instructions; do not pour it down the sink.
●
Wash your hands when finished.
What you need to do
Part 1: becoming familiar with the experiment.
1
Copy the table at the end of this sheet into your notes.
2
Set up the apparatus as shown in the diagram.
3
Carefully measure out 50 cm of sodium thiosulfate solution. Pour it into the conical flask and
measure its temperature.
4
Draw a cross on the scrap piece of paper. Put the flask over the top of the cross.
5
If you look down through the top of the flask you should be able to see the cross clearly.
3
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213
C2 4.2a – Student practical sheet
3
6
Carefully measure out 5 cm of dilute hydrochloric acid. Pour it into the flask containing the
sodium thiosulfate solution. Start the stop clock straightaway.
7
Look down at the cross. The solution will turn cloudy. Time how long it takes for the cross to
‘disappear’. Pour the solution away as quickly as possible.
8
Repeat the experiment at least twice and work out the mean time for the cross to disappear.
Temperature (°C)
Time for cross to disappear (s)
(repeat experiments)
1
2
3
Mean time
Room temperature
9
Once you are confident that you can perform the experiment accurately, stopping the
experiment at the same end point each time, move on to part 2 of the experiment.
Part 2: using the technique at different temperatures
10 Repeat steps 3–7 at different temperatures. Your teacher will provide you with water baths set
at different temperatures above room temperature, plus some cold water or ice baths below
room temperature. Allow your flask with the thiosulfate to heat up (or cool down) before adding
the acid. Record the temperature after the acid has been added and the time taken for the
cross to disappear in a suitable table.
11 Plot a graph of your results (including the room temperature mean), with temperature along the
x-axis and the time taken for the cross to disappear along the y-axis. (6 marks)
Using the evidence
1
Why did you repeat the experiment in part 1? (1 mark)
2
How close were your times for the 3 experiments in part 1? What does that tell you about the
accuracy and reliability of your experiment? (1 mark)
3
Why did the cross ‘disappear’? Do you think that this a very accurate way of measuring the rate
of reaction? (2 marks)
4
For part 2: what were your independent and dependent variables? (2 marks)
5
What other variables did you have to control? (2 marks)
6
What happens to the time taken for the cross to disappear when the temperature is increased?
(1 mark)
7
What happens to the rate of reaction when the temperature is increased? (1 mark)
8
From your graph, roughly what rise in temperature is needed to double the rate of reaction?
(1 mark)
Evaluation
9
How reliable do you think your experiment was? Consider ways in which you might improve
this. (3 marks)
Extension
10 How might this reaction be used to measure the effect of concentration? (3 marks)
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C2 4.2b – Student worksheet
The effect of temperature on rates of reaction
1
Why don’t all collisions between particles result in a chemical reaction? (1 mark)
2
What is the activation energy of a reaction? (1 mark)
3
How could you make sure that more particles have the activation energy in a chemical
reaction? (1 mark)
4
When you mix lead nitrate and potassium nitrate solutions, it changes colour immediately.
What can you say about the activation energy of this reaction? (1 mark)
5
Matches burn vigorously. Why do not they catch fire as soon as they are in contact with oxygen
in the air? (1 mark)
6
When you mix two solutions at 20 °C, they turn cloudy after 2 minutes. When you repeat the
experiment at 30 °C, they turn cloudy after 1 minute. Make two deductions about this
experiment. (2 marks)
7
What would happen if the same experiment were carried out using ice-cold solutions? (1 mark)
8
Steve investigated the reaction between magnesium and hydrochloric acid at 21 °C. He added
3
a 2 cm strip of magnesium to 25 cm of acid, and collected the hydrogen formed in a gas
syringe. Here are his results:
Time (s)
0
10
20
30
40
50
60
70
80
90
Volume of hydrogen (cm3)
0
7
14
21
27
32
36
39
40
40
Plot a graph of these results. The time should go along the x-axis and volume of hydrogen along
the y-axis. (2 marks)
9
Steve then repeated the experiment at 35 °C.
a
What was the total volume of hydrogen collected at 21 °C? (1 mark)
b
Would the volume of gas obtained at 35 °C be the same, less or more? Explain your
answer. (2 marks)
c
Sketch the graph of how you would expect the results of this experiment to look over the
graph you have just drawn for question 9. (1 mark)
10 Explain in terms of collision theory how increasing the temperature affects the rate of a
reaction. (2 marks)
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215
C2 4.3a – Student practical sheet
The effect of concentration on reaction rates
In this experiment you are going to investigate the effect of concentration on the rate of this
reaction:
Magnesium + hydrochloric acid → magnesium chloride + hydrogen
You are going to change the concentration of hydrochloric acid and time how long it takes to collect
3
20 cm of hydrogen. You can change the concentration of acid by diluting it with water.
Aim
To investigate the effect of concentration on the reaction between magnesium ribbon and
hydrochloric acid.
Equipment
●
eye protection
●
stopclock or stopwatch
●
dilute hydrochloric acid
●
gas syringe
●
clamp stand
●
conical flask with bung and delivery tube
●
strips of magnesium
●
rubber tubing
●
measuring cylinder
Safety
●
Wear your eye protection.
●
Wash your hands after handling the metal and acid solutions.
What you need to do
1
3
Copy the table. Notice that the total volume of liquid is the same each time (25 cm ).
Experiment
3
Volume of dilute hydrochloric acid (cm )
3
Volume of water (cm )
1
2
3
4
5
25
20
15
10
5
0
5
10
15
20
Time to produce 20 cm3 of gas (s)
Rate of gas production (rate = 20 cm3/time taken)
2
Set up the apparatus as shown.
3
Measure out 25 cm of dilute hydrochloric
acid and pour it into a conical flask. (This is
experiment 1 in the table.)
4
Trap the magnesium strip between the bung
and side of the flask. This may be difficult.
5
Twist the bung to let the magnesium strip fall
into the acid. Start the stop clock. Time how
3
long it takes to produce 20 cm of hydrogen gas.
6
Repeat the experiment with the other concentrations of acid.
3
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C2 4.3a – Student practical sheet
Using the evidence
1
Plot a graph of your results. (6 marks)
Evaluation
2
Which experiment had the lowest concentration of acid? (1 mark)
3
Which experiment had the highest concentration of acid? (1marks)
4
What happens to the time taken to produce 20 cm of gas when the concentration is increased?
(1 mark)
3
Extension
5
Complete the final row of the table by calculating the rate of gas production. (3 marks)
6
Plot a graph of your rate (cm of gas/second) on the y-axis, and concentration (volume of acid
3
in 25 cm ) on the x-axis. (6 marks)
7
What happens to the rate of gas when the concentration is increased? (1 mark)
8
What is the relationship between ‘time taken’ and rate? (1 mark)
9
Explain your results in terms of collision theory. (2 marks)
3
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217
C2 4.3b – Student worksheet
Concentration and reaction rates
Sodium thiosulfate
+
hydrochloric acid
→
sodium chloride
+
sulfur
+
water
Na2S2O3
+
HCl
→
2NaCl
+
S
+
H2O
3
3
50 cm of a solution of sodium thiosulfate and 5 cm of hydrochloric acid were mixed in a flask over
a piece of paper marked with a cross. Different concentrations of sodium thiosulfate were obtained
by diluting the sodium thiosulfate with water, and the experiment was repeated. These are the
results.
Volume of sodium
thiosulfate solution
used (cm3)
Volume of water
(cm3)
50
0
50
43
40
10
40
53
30
20
30
69
20
30
20
105
10
40
10
243
Mass of sodium
thiosulfate used
(g/dm3)
Time for cross to
disappear (s)
Rate of reaction
(1/time)
1
The reaction rate can be calculated as 1/time taken for the reaction to be complete. Calculate
this value for each concentration of sodium thiosulfate and then write down the values that
should complete the final column. (5 marks)
2
Draw two graphs:
a
time taken (y-axis) against mass of sodium thiosulfate used (x-axis). (2 marks)
b
rate (y-axis) against mass of sodium thiosulfate used (x-axis). (2 marks)
3
How does the rate change as the concentration of sodium thiosulfate increases? (1 mark)
4
a
Why was the total volume kept at 55 cm for each experiment? (1 mark)
b
How was the total volume kept at 55 cm for each experiment? (1 mark)
5
3
3
What is the biggest source of error in this experiment? How could it be minimised? (2 marks)
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C2 4.4a – Student practical sheet
The effect of surface area on reaction rates
In this experiment, you are going to investigate the effect of surface area on the rate of this
reaction:
Calcium carbonate + hydrochloric acid → calcium chloride + carbon dioxide + water
Calcium carbonate is the chemical name for marble. You can change the surface area by breaking
large marble chips into small chips.
Aim
To investigate the effect of surface area on the reaction between calcium carbonate and
hydrochloric acid.
Equipment
●
eye protection
●
top-pan balance
●
large marble chips (about 10 g)
●
small marble chips (about 10 g)
●
dilute hydrochloric acid
●
measuring cylinder
●
cotton wool
●
stopclock
Safety
●
Wear your eye protection.
●
Wash your hands after handling the marble chips and acid solution.
What you need to do
1
Copy this table. Leave 20 rows for your results because the reaction may take a long time to
finish.
Time (s)
Experiment 1 (large chips)
Mass (g)
Total loss in mass (g)
Experiment 2 (small chips)
Mass (g)
Total loss in mass (g)
0
30
60
90
2
Put the large marble chips into a conical flask and put the flask on the top-pan balance.
3
Measure out 40 cm of dilute acid in a measuring cylinder.
3
Measure the total mass of the flask, marble chips, cotton wool, measuring cylinder and acid.
This is the mass at ‘time zero’ (the mass at the start of the experiment).
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219
C2 4.4a – Student practical sheet
4
Carefully pour the acid into the flask and put the cotton wool plug in the neck of the flask.
Leave the measuring cylinder on the top-pan balance. Start the stopclock straightaway. Some
balances have a ‘tare’ button. You should press this as soon as you start timing. The balance
will give you the loss in mass directly.
5
Read the mass shown on the balance after 30 seconds, 60 seconds, 90 seconds and so on.
6
Carry on reading the mass every 30 seconds until the reaction has finished. The mass stops
going down when the reaction has finished. Take mass readings for another 60 seconds after
the reaction has finished.
7
Repeat the experiment using the small chips.
Using the evidence
1
Plot a graph of loss in mass (in grams) against time (in seconds). Use the same axes for both
the small chips and the large chips. Draw smooth curves through the points. (9 marks)
2
How did you keep the experiment a fair test? (2 marks)
3
a
Which have the larger surface area, large chips or small chips? (1 marks)
b
Which chips gave the fastest reaction? How can you tell from the graphs? (2 marks)
c
Write down what you have found out from the results of the experiment. (1 marks)
d
Try and explain your results using the collision theory. (3 marks)
Evaluation
4
How could you develop this experiment to make it more quantitative? (2 marks)
Extension
5
A fine powder would in theory have the greatest surface area. Suggest why this might not be
the case under ordinary circumstances? (What will the powder tend to do?) (2 marks)
6
Convert your time graphs to rate graphs (mass loss/time taken) and comment on the
relationship. (14 marks)
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C2 4.4b – Student worksheet
Investigating the effect of surface area
Students carried out an experiment to study the reaction between marble chips and hydrochloric
acid. They wanted to see what effect changing the surface area of the marble chips had on the rate
of reaction.
3
They used 5 g of marble and 25 cm of dilute acid. They used the ‘loss in mass’ method. Here are
their results using two different sizes of marble chips, A and B. In both cases, all the marble
dissolved.
Time (min)
0
1
2
3
4
5
6
7
Loss in mass (g) –
sample A
0
0.46
0.84
1.10
1.29
1.38
1.38
1.38
Loss in mass (g) –
sample B
0
0.36
0.68
0.92
1.09
1.24
1.38
1.38
1
Write word and balanced chemical equations for this reaction; use CaCO3, HCl, CaCl2, H2O,
CO2. (3 marks)
2
Plot a graph of these results. Label the curves A and B. (3 marks)
3
Which chips have the larger surface area, A or B? (1 mark)
4
Which were the smaller chips, A or B? (1 mark)
5
Explain how chip size affects total surface area (for the same mass of chips). (1 mark)
6
Comment on the final mass loss in each case. (2 marks)
7
The students then repeated the experiment using 5 g of marble powder (sample C) and 25 cm
of the same dilute acid. The results are shown here.
Time (min)
0
1
2
3
4
5
6
7
Loss in mass (g) –
sample C
0
0.15
1.10
1.39
1.49
1.49
1.49
1.49
8
a
Plot the graph of these results on your graph for A and B. Label the curve C. (2 marks)
b
Look at the results for C. Describe two examples of results that are unexpected and one
instance where the results show an expected trend. Try to explain how the unexpected
results could have been obtained. (5 marks)
3
The chemical name for marble is calcium carbonate. Other metal carbonates react in a similar
way. Write word and balanced symbol equations for the reaction between zinc carbonate and
hydrochloric acid. You may find these formulae useful: ZnCO3, ZnCl2. (3 marks)
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221
C2 4.5a – Student practical sheet
The effects of different catalysts on reaction
rates
A catalyst speeds up a chemical reaction. Different catalysts are used to speed up different
reactions. In this investigation, you are going to find out the best catalyst for the following reaction:
Hydrogen peroxide → water + oxygen
Without a catalyst, oxygen is formed very slowly. If the reaction is speeded up, the oxygen will be
made faster. You can see bubbles forming in the hydrogen peroxide solution.
Aim
To investigate the effect of different catalysts on the decomposition of hydrogen peroxide.
Equipment
●
eye protection
●
four test tubes in a rack
●
detergent
●
spatula
●
catalyst selection: copper(II) oxide, iron(III)
oxide, aluminium oxide, manganese(IV)
oxide, silicon dioxide (sand)
●
20-volume hydrogen peroxide
●
small measuring cylinder
●
stopclock or stopwatch
●
elastic bands
Safety
●
Wear your eye protection.
●
20-volume hydrogen peroxide is an irritant; keep it off your skin.
●
Treat the catalysts as harmful and irritant and wash your hands when you have finished.
What you need to do
3
1
Measure 5 cm hydrogen peroxide into the test tube and add two drops of detergent.
2
Add half a spatula-full of iron(III) oxide to the tube. Watch what happens
3
Working in groups, think of a way to measure how far the foam of bubbles rises in the tube in a
set time. You may need to try more than one way to measure this.
4
Once you have decided on how you will perform this experiment, draw up a suitable table for
your results.
5
Perform your test on each catalyst in turn, starting with fresh hydrogen peroxide in a clean tube
each time.
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C2 4.5a – Student practical sheet
Using the evidence
1
Give one difficulty in measuring the rate of rise of the foam in the tube. (1 mark)
2
Which sample of catalyst produced the best (fastest) result? (1 mark)
3
Was this a fair test? (2 marks)
Evaluation
4
How was each sample of catalyst measured out? (1 mark)
5
If different people each measured half a spatula of solid, would the amounts used be the
same? Explain your answer. (2 marks)
6
If there is any variability in the amounts measured, do you think that it has an important effect
on your results? Explain your answer. (3 marks)
7
Suggest one other way of measuring solids that would reduce inaccuracies. (1 mark)
Extension
8
Were there any factors in your experiment that were not carefully controlled? If so, suggest
ways to improve on your experimental design. (2 marks)
9
Catalyst particle size is very important. Why is that? (2 marks)
10 In another experiment, a student tested the effect of iron(III) oxide in three forms: coarse
grains, fine grains and fine powder. Describe the likely outcome, explaining why you think this
would happen. (2 marks)
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223
C2 4.5b – Student worksheet
Catalysts
Hydrogen peroxide decomposes to form water and oxygen:
Hydrogen peroxide → water + oxygen
2H2O2 → 2H2O + O2
A student investigated the effect of different metal oxides on the decomposition of hydrogen
3
peroxide. She placed 50 cm of hydrogen peroxide solution in a conical flask and attached it to a
gas syringe. She then added one spatula of copper oxide to the hydrogen peroxide, started a clock
and found the volume of oxygen produced at 20-second intervals. She then repeated the
experiment, once with the same amount of manganese oxide and then a second time with the
same amount of zinc oxide. These are her results.
Time (s)
Volume of oxygen
(cm3) using
copper oxide
Volume of oxygen
(cm3) using
manganese oxide
Volume of oxygen
(cm3) using zinc
oxide
0
0
0
0
20
1
5
0
40
2
9
0
60
3
13
0
80
4
17
0
100
5
21
0
120
6
24
0
140
7
27
0
160
8
29
0
180
9
30
0
1
Plot the results on a graph. Use the same axes for all the graphs. Time should be on the x-axis.
(4 marks)
2
Which of these three metal oxides is the best catalyst? Explain your answer. (2 marks)
3
a
Calculate the volume of oxygen produced per second for the first 60 seconds of the fastest
reaction, and then for the last 60 seconds of the fastest reaction. (4 marks)
a
How has the rate changed? (1 mark)
b
Why has the rate changed? (1 mark)
4
Which variables should be kept constant during the three experiments? (3 marks)
5
Helen used a spatula measure of the solid metal oxide in each experiment.
a
Is this always the same amount? Explain your answer. (2 marks)
b
How could she have made the experiment a fairer comparison? (1 mark)
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C2 4.5c – Student worksheet
Catalysts in industry
Enzymes are natural catalysts that are very efficient in changing the rate of reactions. Since
enzymes are protein molecules, they are affected by temperature changes. Just as the human
body has a normal temperature of 37 °C at which its chemical reactions work best, so enzymes
also work best at particular temperatures.
A student investigated the effect of temperature on an enzyme-catalysed reaction. Here are the
results.
Temperature
(°C)
10
20
30
40
50
60
Rate of
reaction
1
1.8
4
5.5
1.2
0.8
1
Plot these results on a graph of rate (y-axis) against temperature. (2 marks)
2
Describe the shape of the graph. (2 marks)
3
How does raising the temperature affect the rate? (2 marks)
4
What is the optimum temperature for this reaction? (1 mark)
5
Where would it be useful to have some extra results to improve the reliability of the graph?
(1 mark)
6
Proteins can be denatured at high temperatures. How does this help explain the graph?
(1 mark)
7
By how much does the rate increase between 20 and 30 °C? (2 marks)
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