Exam code: 0653
Which statement explains how a catalyst increases the rate of a chemical reaction?
It increases the energy of the particles in the reaction mixture.
It increases the minimum energy that colliding particles must have to react.
It reduces the energy of the particles in the reaction mixture.
It reduces the minimum energy that colliding particles must have to react.
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Iron reacts with dilute hydrochloric acid to form hydrogen and a salt.
(i) Explain why this is a chemical change.
[1]
(ii) State the test for hydrogen and give the observation for a positive result.
test .................................................
observation .....................................
[1]
Iron is used as a catalyst in some chemical reactions.
Describe what is meant by a catalyst.
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Calcium carbonate reacts with dilute hydrochloric acid to produce calcium chloride.
(i) State the names of the other two products in this reaction.
[2]
(ii) The rate of this reaction can be increased by increasing the temperature of the hydrochloric acid.
Explain why.
Use ideas about particle collisions and energy in your answer.
[2]
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Procedure
Set up the apparatus as shown in Fig. 3.1.
Fig. 3.1
Use the 10 cm3 measuring cylinder to measure 10 cm3 of dilute sulfuric acid.
Remove the stopper from the boiling tube.
Add the dilute sulfuric acid to the boiling tube.
Add about 1 cm3 of aqueous copper(II) sulfate to the boiling tube.
Add a spatula of metal F to the boiling tube.
Put the stopper back into the boiling tube and start the stop-watch.
(i) Record in Table 3.1 the time taken to collect 5 cm3 , 10 cm3 , 15 cm3 , 20 cm3 and 25 cm3 of gas.
Record each time to the nearest second.
Table 3.1
volume of gas collected / cm3 | time taken / s |
5 | |
10 | |
15 | |
20 | |
25 |
[3]
(ii) State the independent variable and the dependent variable in this investigation.
independent variable ......................................................................................................... dependent variable ............................................................................................................
[1]
(iii) On the grid, plot a graph of volume of gas collected (vertical axis) against time taken.
[3]
(iv) Draw the line of best fit.
[1]
(v) Describe the relationship between the volume of gas collected and the time taken.
[1]
(vi) Suggest one possible source of error in the measurement of the time taken.
[1]
(vii) Suggest one way to obtain a more accurate measurement of the volume of gas collected.
[1]
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Procedure
The student:
uses a measuring cylinder to measure 10 cm3 of dilute sulfuric acid
adds the dilute sulfuric acid to a boiling tube
sets up apparatus as shown in Fig. 3.1
Fig. 3.1
removes the stopper from the boiling tube
adds one spatula of metal F to the boiling tube
puts the stopper back into the boiling tube and starts the stop-watch
records in Table 3.1 the time taken to collect 5 cm3 , 10 cm3 , 15 cm3 , 20 cm3 and 25 cm3 of gas.
(i) Fig. 3.2 shows the stop-watch readings for 5 cm3 and 25 cm3 of gas collected.
Fig.3.2
Record in Table 3.1 the time taken to the nearest second to collect 5 cm3 and 25 cm3 of gas.
Table 3.1
volume of gas collected / cm³ | time taken / s |
5 | |
10 | 22 |
15 | 34 |
20 | 46 |
25 |
[2]
(ii) State the independent variable and the dependent variable in this investigation.
[1]
(iii) On the grid, plot a graph of volume of gas collected (vertical axis) against time taken.
[3]
(iv) Draw the line of best fit.
[1]
(v) Describe the relationship between the volume of gas collected and the time taken.
[1]
(vi) Suggest one possible source of error in the measurement of the time taken.
[1]
(vii) Suggest one way to obtain a more accurate measurement of the volume of gas collected.
[1]
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