1.	Which statements describe the action of a catalyst?
I.	It does not alter the ∆H for a reaction.
II.	It increases the Ea for the reaction.
III.	It alters the mechanism (pathway) of a reaction.
A.	I and II only
B.	I and III only
C.	II and III only
D.	I, II and III
(Total 1 mark)

2.	Consider the reaction between gaseous iodine and gaseous hydrogen.
		I2(g) + H2(g)  2HI(g)	∆HO = –9 kJ
	Why do some collisions between iodine and hydrogen not result in the formation of the product?
A.	The I2 and H2 molecules do not have sufficient energy.
B.	The system is in equilibrium.
C.	The temperature of the system is too high.
D.	The activation energy for this reaction is very low.
(Total 1 mark)

3.	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)

4.	At 25 °C, 200 cm3 of 1.0 mol dm–3 nitric acid is added to 5.0 g of magnesium powder. If the experiment is repeated using the same mass of magnesium powder, which conditions will result in the same initial reaction rate?

	Volume of HNO3 / cm3	Concentration of
HNO3 / mol dm–3	Temperature / °C	
A.	200	2.0	25	
B.	200	1.0	50	
C.	100	2.0	25	
D.	100	1.0	25	
(Total 1 mark)

5.	Factors that affect the rate of a chemical reaction include particle size, concentration of reactants and the temperature of the reaction.
(i)	Define the term rate of a chemical reaction.
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(1)
 
(ii)	List the three characteristic properties of reactant particles which affect the rate of reaction as described by the collision theory.
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(3)
(Total 4 marks)

6.	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)

7.	Sodium carbonate and hydrochloric acid react according to the equation below.
		Na2CO3(s) + 2HCl(aq) → CO2(g) + 2NaCl(aq) + H2O(l)
	Which conditions will produce the fastest initial rate with 2.0 g of powdered sodium carbonate?
A.	100 cm3 of 1.0 mol dm–3 hydrochloric acid at 323 K
B.	50 cm3 of 2.0 mol dm–3 hydrochloric acid at 323 K
C.	100 cm3 of 1.0 mol dm–3 hydrochloric acid at 348 K
D.	50 cm3 of 2.0 mol dm–3 hydrochloric acid at 348 K
(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.	Powdered manganese(IV) oxide, MnO2(s), increases the rate of the decomposition reaction of hydrogen peroxide, H2O2(aq). Which statements about MnO2 are correct?
I.	The rate is independent of the particle size of MnO2.
II.	MnO2 provides an alternative reaction pathway for the decomposition with a lower activation energy.
III.	All the MnO2 is present after the decomposition of the hydrogen peroxide is complete.
A.	I and II only
B.	I and III only
C.	II and III only
D.	I, II and III
(Total 1 mark)

10.	Alex and Hannah were asked to investigate the kinetics involved in the iodination of propanone.
They were given the following equation by their teacher.
		CH3COCH3(aq) + I2(aq)  CH2ICOCH3(aq) + HI(aq)
	Alex’s hypothesis was that the rate will be affected by changing the concentrations of the propanone and the iodine, as the reaction can happen without a catalyst. Hannah’s hypothesis was that as the catalyst is involved in the reaction, the concentrations of the propanone, iodine and the hydrogen ions will all affect the rate.
	They carried out several experiments varying the concentration of one of the reactants or the catalyst whilst keeping other concentrations and conditions the same. Their results are shown graphically below.

(a)	Discuss whether either Alex’s or Hannah’s hypothesis is correct.
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(2)
 
(b)	Explain why the reaction rate will increase with increasing temperature.
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(2)

(c)	(i)	This reaction uses a catalyst. Sketch and annotate the Maxwell-Boltzmann energy distribution curve for a reaction with and without a catalyst on labelled axes below.

(3)
 
(ii)	Describe how a catalyst works.
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(1)
(Total 8 marks)

11.	Which unit could be used for the rate of a chemical reaction?
A.	mol
B.	mol dm–3
C.	mol dm–3 s–1
D.	dm3
(Total 1 mark)

12.	Which of the following can increase the rate of a chemical reaction?
I.	Increasing the temperature
II.	Adding a catalyst
III.	Increasing the concentration of reactants
A.	I and II only
B.	I and III only
C.	II and III only
D.	I, II and III
(Total 1 mark)

13.	The graph below shows how the volume of carbon dioxide formed varies with time when a hydrochloric acid solution is added to excess calcium carbonate in a flask.

(i)	Explain the shape of the curve.
(3)
 
(ii)	Copy the above graph on your answer sheet and sketch the curve you would obtain if double the volume of hydrochloric acid solution of half the concentration as in the example above is used instead, with all other variables kept constant from the original. Explain why the shape of the curve is different.
(4)

(iii)	Outline one other way in which the rate of this reaction can be studied in a school laboratory. Sketch a graph to illustrate how the selected variable would change with time.
(2)
 
(iv)	Define the term activation energy and state one reason why the reaction between calcium carbonate and hydrochloric acid takes place at a reasonably fast rate at room temperature.
(2)
(Total 11 marks)

14.	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)

15.	Which changes increase the rate of the reaction below?
		C4H10(g) + Cl2(g) → C4H9Cl(l) + HCl(g)
I.	Increase of pressure
II.	Increase of temperature
III.	Removal of HCl(g)
A.	I and II only
B.	I and III only
C.	II and III only
D.	I, II and III
(Total 1 mark)

16.	The Haber process enables the large-scale production of ammonia needed to make fertilizers.
	The equation for the Haber process is given below.
		N2(g) + 3H2  2NH3(g)
	The percentage of ammonia in the equilibrium mixture varies with temperature.

(i)	Use the graph to deduce whether the forward reaction is exothermic or endothermic and explain your choice.
(2)
 
(ii)	State and explain the effect of increasing the pressure on the yield of ammonia.
(2)
 
(iii)	Explain the effect of increasing the temperature on the rate of reaction.
(2)
(Total 6 marks)

17.	What is the best definition of rate of reaction?
A.	The time it takes to use up all the reactants
B.	The rate at which all the reactants are used up
C.	The time it takes for one of the reactants to be used up
D.	The increase in concentration of a product per unit time
(Total 1 mark)

18.	Which factors can affect reaction rate?
I.	The state of the reactants
II.	The frequency of the collisions between particles
III.	The average kinetic energy of the particles
A.	I and II only
B.	I and III only
C.	II and III only
D.	I, II and III
(Total 1 mark)

19.	Equal masses of powdered calcium carbonate were added to separate solutions of hydrochloric acid. The calcium carbonate was in excess. The volume of carbon dioxide produced was measured at regular intervals. Which curves best represent the evolution of carbon dioxide against time for the acid solutions shown in the table below.

	25 cm3 of 2 mol dm–3 HCl	50 cm3 of 1 mol dm–3 HCl	25 cm3 of 1 mol dm–3 HCl	
A.	I	III	IV	
B.	I	IV	III	
C.	I	II	III	
D.	II	I	III	
(Total 1 mark)

20.	What is the function of iron in the Haber process?
A.	It shifts the position of equilibrium towards the products.
B.	It decreases the rate of the reaction.
C.	It provides an alternative reaction pathway with a lower activation energy.
D.	It reduces the enthalpy change of the reaction.
(Total 1 mark)

21.	(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)

22.	(i)	Define the term rate of reaction.
(1)

(ii)	State an equation for the reaction of magnesium carbonate with dilute hydrochloric acid.
(1)
 
(iii)	The rate of this reaction in (ii), can be studied by measuring the volume of gas collected over a period of time. Sketch a graph which shows how the volume of gas collected changes with time.
(1)
 
(iv)	The experiment is repeated using a sample of hydrochloric acid with double the volume, but half the concentration of the original acid. Draw a second line on the graph you sketched in part (iii) to show the results in this experiment. Explain why this line is different from the original line.
(4)
(Total 7 marks)

23.	Hydrochloric acid is reacted with large pieces of calcium carbonate, the reaction is then repeated using calcium carbonate powder. How does this change affect the activation energy and the collision frequency?

	Activation energy	Collision frequency	
A.	increases	increases	
B.	stays constant	increases	
C.	increases	stays constant	
D.	stays constant	stays constant	
(Total 1 mark)

24.	Which statement is true about using sulfuric acid as a catalyst in the following reaction?
		CH3–CO–CH3(aq) + I2(aq)  CH3–CO–CH2–I(aq) + HI(aq)
I.	The catalyst increases the rate of reaction.
II.	The catalyst lowers the activation energy for the reaction.
III.	The catalyst has been consumed at the end of the chemical reaction.
A.	I and II only
B.	I and III only
C.	II and III only
D.	I, II and III
(Total 1 mark)

25.	Graphing is an important method in the study of the rates of chemical reaction. Sketch a graph to show how the reactant concentration changes with time in a typical chemical reaction taking place in solution. Show how the rate of the reaction at a particular time can be determined.
(Total 4 marks)

26.	(a)	A solution of hydrogen peroxide, H2O2, is added to a solution of sodium iodide, NaI, acidified with hydrochloric acid, HCl. The yellow colour of the iodine, I2, can be used to determine the rate of reaction.
		H2O2(aq) + 2NaI(aq) + 2HCl(aq) → 2NaCl(aq) + I2(aq) + 2H2O(l)
 
	The experiment is repeated with some changes to the reaction conditions. For each of the changes that follow, predict, stating a reason, its effect on the rate of reaction.
(i)	The concentration of H2O2 is increased at constant temperature.
(2)
 
(ii)	The solution of NaI is prepared from a fine powder instead of large crystals.
(2)

(b)	Explain why the rate of a reaction increases when the temperature of the system increases.
(3)
(Total 7 marks)

27.	Excess magnesium, was added to a beaker of aqueous hydrochloric acid. A graph of the mass of the beaker and contents was plotted against time (line 1).

	What change in the experiment could give line 2?
A.	The same mass of magnesium in smaller pieces
B.	The same volume of a more concentrated solution of hydrochloric acid
C.	A lower temperature
D.	A more accurate instrument to measure the time
(Total 1 mark)

28.	Which quantities in the enthalpy level diagram are altered by the use of a catalyst?

A.	I and II only
B.	I and III only
C.	II and III only
D.	I, II and III
(Total 1 mark)