1.	Which is the correct relationship between enthalpy of vaporization, intermolecular forces and boiling point?

	Enthalpy of vaporization	Intermolecular forces	Boiling point	
A.	small	weak	high	
B.	small	strong	low	
C.	large	weak	high	
D.	large	strong	high	
(Total 1 mark)

2.	On the axes below sketch two Maxwell-Boltzmann energy distribution curves for the same sample of gas, one at a temperature T and another at a higher temperature . Label both axes. Explain why raising the temperature increases the rate of a chemical reaction.

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(Total 5 marks)

3.	(a)	Define the term activation energy, Ea.
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(1)
 
(b)	State two conditions necessary for a reaction to take place between two reactant particles.
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(2)
 
(c)	Sketch an enthalpy level diagram to describe the effect of a catalyst on an exothermic reaction.

(3)
(Total 6 marks)

4.	The rate information below was obtained for the following reaction at a constant temperature.
		2NO2(g) + F2(g) → 2NO2F(g)

[NO2] / mol dm–3	[F2] / mol dm–3	Rate / mol dm–3 s–1	
2.0 × 10–3	1.0 × 10–2	4.0 × 10–4	
4.0 × 10–3	1.0 × 10–2	8.0 × 10–4	
4.0 × 10–3	2.0 × 10–2	1.6 × 10–3	
	What are the orders of the reaction with respect to NO2 and F2?
A.	NO2 is first order and F2 is second order
B.	NO2 is second order and F2 is first order
C.	NO2 is first order and F2 is first order
D.	NO2 is second order and F2 is second order
(Total 1 mark)

5.	Which affects the equilibrium vapour pressure of a liquid in a sealed container, assuming that there is always some of the liquid present?
A.	The temperature of the liquid
B.	The surface area of the liquid
C.	The volume of the liquid
D.	The volume of the container
(Total 1 mark)

6.	The equilibrium between nitrogen dioxide, NO2, and dinitrogen tetroxide, N2O4, is shown below.
		2NO2(g)  N2O4(g)	Kc = 0.01
	What happens when the volume of a mixture at equilibrium is decreased at a constant temperature?
I.	The value of Kc increases
II.	More N2O4 is formed
III.	The ratio of  decreases
A.	I and II only
B.	I and III only
C.	II and III only
D.	I, II and III
(Total 1 mark)

7.	0.50 mol of I2(g) and 0.50 mol of Br2(g) are placed in a closed flask. The following equilibrium is established.
		I2(g) + Br2(g)  IBr(g)
	The equilibrium mixture contains 0.80 mol of IBr(g). What is the value of Kc?
A.	0.64
B.	1.3
C.	2.6
D.	64
(Total 1 mark)

8.	Under which conditions will the reaction between 1.0 g calcium carbonate and excess hydrochloric acid be the fastest? Assume that all reactions are carried out at the same temperature.
A.	One large piece of calcium carbonate and 2 mol dm–3 hydrochloric acid
B.	One large piece of calcium carbonate and 1 mol dm–3 hydrochloric acid
C.	Powdered calcium carbonate and 2 mol dm–3 hydrochloric acid
D.	Powdered calcium carbonate and 1 mol dm–3 hydrochloric acid
(Total 1 mark)

9.	Curve X on the graph below shows the volume of oxygen formed during the catalytic decomposition of a 1.0 mol dm–3 solution of hydrogen peroxide.
		2H2O2(aq) → O2(g) + 2H2O(l)
		
	Which change would produce the curve Y?
A.	Adding water
B.	Adding some 0.1 mol dm–3 hydrogen peroxide solution
C.	Using a different catalyst
D.	Lowering the temperature
(Total 1 mark)

10.	A piece of zinc was added to aqueous nitric acid and the volume of hydrogen gas produced was measured every minute. The results are plotted on the graph below.
		
	Which graph would you expect if the same mass of powdered zinc was added to nitric acid with the same concentration?
		
(Total 1 mark)

11.	An example of a homogeneous reversible reaction is the reaction between hydrogen and iodine.
		H2(g) + I2(g)  2HI(g)
(i)	Outline the characteristics of a homogeneous chemical system that is in a state of equilibrium.
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(2)
 
(ii)	Deduce the expression for the equilibrium constant, Kc.
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(1)
 
(iii)	Predict what would happen to the position of equilibrium and the value of Kc if the pressure is increased from 1 atm to 2 atm.
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(2)
 
(iv)	The value of Kc at 500 K is 160 and the value of Kc at 700 K is 54. Deduce what this information tells us about the enthalpy change of the forward reaction.
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(1)

(v)	The reaction can be catalysed by adding platinum metal. State and explain what effect the addition of platinum would have on the value of the equilibrium constant.
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(2)
(Total 8 marks)

12.	Sodium thiosulfate solution, Na2S2O3(aq), and hydrochloric acid, HCl(aq), react spontaneously to produce solid sulfur, S(s), according to the equation below.
		S2O32–(aq) + 2H+(aq) → S(s) + SO2(aq) + H2O(l)
	A student experimentally determined the rate expression to be:
		rate = k[S2O32–(aq)]2
	Which graph is consistent with this information?

(Total 1 mark)

13.	Consider the following equilibrium reaction.
		Cl2(g) +  SO2(g)  SO2Cl2(g)	∆HO = –84.5 kJ
	In a 1.00 dm3 closed container, at 375 °C, 8.60 × 10–3 mol of SO2 and 8.60 × 10–3 mol of Cl2 were introduced. At equilibrium, 7.65 × 10–4 mol of SO2Cl2 was formed.

(i)	Deduce the equilibrium constant expression, Kc, for the reaction.
(1)
 
(ii)	Determine the value of the equilibrium constant, Kc.
(3)
(iii)	If the temperature of the reaction is changed to 300 °C, predict, stating a reason in each case, whether the equilibrium concentration of SO2Cl2 and the value of Kc will increase or decrease.
(3)
 
(iv)	If the volume of the container is changed to 1.50 dm3, predict, stating a reason in each case, how this will affect the equilibrium concentration of SO2Cl2 and the value of Kc.
(3)
 
(v)	Suggest, stating a reason, how the addition of a catalyst at constant pressure and temperature will affect the equilibrium concentration of SO2Cl2.
(2)
(Total 12 marks)

14.	Bromine and nitrogen(II) oxide react according to the following equation.
		Br2(g) + 2NO(g) → 2NOBr(g)
	Which rate equation is consistent with the experimental data?

[Br2] / mol dm–3	[NO] / mol dm–3	Rate / mol dm–3 s–1	
0.10	0.10	1.0 × 10–6	
0.20	0.10	4.0 × 10–6	
0.20	0.40	4.0 × 10–6	
A.	rate = k[Br2]2 [NO]
B.	rate = k[Br2] [NO]2
C.	rate = k[Br2]2
D.	rate = k[NO]2
(Total 1 mark)