Test 1 As Chemistry Unit 2 - Kinetics
Test 1 As Chemistry Unit 2 - Kinetics
Test 1 As Chemistry Unit 2 - Kinetics
Test 1
1.
Cars are fitted with catalytic converters in order to reduce the pollution caused by the
combustion of petrol. Potential pollutant gases include carbon monoxide, nitrogen monoxide
and unburnt hydrocarbons. The first two compounds are removed by passing the hot gases
over a platinum catalyst.
CO(g) + NO(g) CO2(g) +
1
2
N2(g)
H = 373 kJ mol1
(a)
(i)
(ii)
(b)
(i)
Fraction of molecules
with a given energy
Energy
(3)
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(ii)
Use the diagram to explain why the rate of a reaction, such as that between
carbon monoxide and nitrogen monoxide, will change as the temperature
increases.
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(2)
(c)
The reaction between carbon monoxide and nitrogen monoxide requires a platinum
catalyst with a large surface area. Explain the effect of a catalyst on the rate of this
reaction and why the surface area needs to be large.
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(4)
(Total 11 marks)
2.
Number
of
molecules
Energy
(3)
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(b)
Use your diagram and the idea of activation energy to explain why the rate of a
chemical reaction increases with increasing temperature.
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(4)
(Total 7 marks)
3.
In a series of experiments to investigate the factors which control the rate of a chemical
reaction, aqueous hydrochloric acid was added to calcium carbonate in a conical flask placed
on an electronic balance.
The loss in mass of the flask and its contents was recorded for 15 minutes.
CaCO3(s) + 2HCl(aq) CaCl2(aq) + H2O(l) + CO2(g)
Calcium carbonate
Hydrochloric acid
Small pieces
Small pieces
Small pieces
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(a)
The results of Experiment 1 give the curve shown on the graph below.
Mass loss/g
2.00
1.50
1.00
Expt. 1
0.50
(i)
10
15
Time/min
(ii)
(b)
Draw curves on the graph to represent the results you would expect for Experiments
2, 3 and 4. Label the curves 2, 3 and 4.
(3)
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(c)
(i)
Calculate the mass of calcium carbonate which exactly reacts with 50.0 cm3 of
1.00 mol dm3 aqueous hydrochloric acid. Mr(CaCO3) = 100.
(3)
(ii)
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4.
(a)
(i)
State two factors other than a change in temperature or the use of a catalyst that
influence the rate of a chemical reaction.
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(2)
(ii)
For one of the factors you have chosen explain the effect on the rate.
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(2)
(b)
Number of
molecules with
energy E
T1
Energy E
(i)
On the same axes draw a similar curve for a reaction mixture at a higher
temperature T2.
(2)
(ii)
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(iii)
Use your answers to parts (i) and (ii) to explain why an increase in temperature
causes an increase in the reaction rate.
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(3)
(Total 10 marks)
5.
(a)
(i)
(2)
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(ii)
Catalysts are used in the exhausts of modem motor cars to speed up the reaction
between polluting gases (carbon monoxide, CO, and dinitrogen oxide, N2O)
before they reach the end of the exhaust pipe.
Use the diagram in (a)(i) to explain how the catalyst achieves this.
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(4)
(b) State ONE other method of increasing the rate of the reaction between two
gases in general. Explain how the collision theory supports your suggested method.
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(3)
(Total 9 marks)
Redington College
Kajana Sivarasa
6.
Two experiments are carried out under the same conditions except that in one
experiment the manganese(IV) oxide is a fine powder and in the other the same mass
of coarse granules is used.
Which experiment would show the faster rate of decomposition? Explain your answer
in terms of collision theory.
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(2)
(b)
(i)
(4)
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(ii)
Mark on your graph a suitable value for the activation energy, Ea, for the
reaction between the gases. Use your drawing to account for the increase in
reaction rate with increasing temperature.
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(3)
(iii)
Redington College
10
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