Section A

1. The rate of a chemical reaction cannot be determine by measuring A the volume of gas liberated per unit time. B the formation of precipitate per unit time. C the change of colour per unit time. D the change of size of solid per unit time.

2. Table shows the volume of oxygen gas liberated at each interval of 4 minutes when a little manganese (IV) oxide powder is added to hydrogen peroxide solution.

Time interval

(min)Volume of oxygen

(cm3)0 – 4 284 – 8 188 – 12 612 – 16 216 – 20 0

Which of the following conclusions can be made based on the information in the above table?I total volume of oxygen gas liberated is 54 cm3.II Hydrogen peroxide is completely decomposed during the time interval of 16 to 20 min.III rate of decomposition of hydrogen peroxide decreases with time.IV total volume of oxygen gas liberated depends on the mass of manganese (IV) oxide used.A I and III onlyB II and IV onlyC I, II and III onlyD I, II, III and IV

3. In an experiment, a little manganese (IV) oxide powder, as a catalyst , is added to 20 cm3 of sodium chlorate (I) solution. The graph for the volume of oxygen gas liberated against time is shown below.

The instantaneous rate of liberation of oxygen gas at 60 seconds, in cm3s-1, is A 72 B 0

C

D

4. A conical flask excess dilute nitric acid and a piece of marble is placed on an electronic balance, as shown in figure.

The mass of the conical flask and its contents is recorded at regular time intervals. Which of the following graphs shows the correct plot of the mass of conical flask and its contents against time?

5. Table shows the reading conditions for two sets of experiments.

Set Reacting conditionsI 0.5 g of zinc powder + 25 cm3 of 0.1 mol dm-3 hydrochloric acid at

room temperature and pressure.II 0.5 g of granulated zinc + 25 cm3 of 0.1 mol dm-3 hydrochloric acid at

room temperature and pressure.

Which of the curves, x, y and z match the experimental results of sets I and II ?

Set I Set IIA Y XB Z YC X ZD Y Z

6. Table shows the quantities of reactants used in four sets of experiments.

Set Quantities of reactantsI 1 g of magnesium powder is added to 5 cm3 of 1 mol dm-3 hydrochloric acid.II 1 g of magnesium ribbon is added to 5 cm3 of 2 mol dm-3 hydrochloric acid.III 1 g of magnesium powder is added to 25 cm3 of 1 mol dm-3 hydrochloric

acid.IV 1 g of magnesium powder is added to 5 cm3 of 1 mol dm-3 sulphuric acid.

Which of the experiments shows the highest initial rate of reaction?A IB IIC IIID IV

7. Which of the following reacting conditions must be kept constant in order to investigate the effect of concentration of hydrochloric acid on the rate of reaction

between magnesium and dilute hydrochloric acid? I volume of hydrochloric acid used. II mass of magnesium used III temperature of the reacting mixture IV total surface area of magnesium used. A I and III only B II and IV only C I, II and III only D I, II, III and IV

8. 5 g of zinc powder is added to 100 cm3 of 1 mol dm-3 sulphuric acid in an experiment. What is the effect on the initial rate of reaction and the total volume of hydrogen collected if the experiment is repeated by adding a few drops of copper (II) sulphate solution to the reacting mixture?

Initial rate Total volume of hydrogen

A Increase IncreaseB Increase No changeC No change IncreaseD No change No change

9. Figure shows an energy level diagram.

Based on the energy level diagram, the activation energy for the reaction R + S → T + W is

A mB nC pD q

10. At 70 0C, the liberation of oxygen gas from the decomposition of hydrogen peroxide solution catalysed by manganese (IV) oxide is faster than that occurring at 28 0C. This is because at higher temperature, I hydrogen peroxide molecules move faster II pressure in the container increases III kinetic energy of the hydrogen peroxide molecules is higher. IV activation energy is lower. A I and III only B I and IV only C II and III only D II and IV only

Section B

1. Figure shows the set-up of the apparatus for an experiment to investigate the rate of reaction between zinc and dilute hydrochloric acid.

(a) (i) Name the products formed in this experiment.

………………………………………………………………………………[2 marks]

(ii) Write down the equation for the reaction that occurs.

………………………………………………………………………………[1 mark]

(b) Name the method used to collect the gas M.

……………………………………………………………………………………..[1 mark]

(c) Zinc metal pieces are substituted by zinc powder of the same mass.(i) What is the effect on the rate of reaction that will be observed?

………………………………………………………………………………[1 mark]

(ii) Use the collision theory to explain your answer to (c)(i).

……………………………………………………………………………..

…………………………………………………………………………….

…………………………………………………………………………….[3 marks]

(iii) On the same axes, sketch the two graphs to represent the respective rates of reaction obtained when zinc metal pieces and zinc powder are used.

[3 marks]

(d) If the mass of zinc used in the experiment is in excess, what will happen if the concentration of the hydrochloric acid is increased to 1.0 mol dm-3?

………………………………………………………………………………………

………………………………………………………………………………………[2 marks]

(e) Explain your answer at (d)

………………………………………………………………………………………

………………………………………………………………………………………[2 marks]

2. The decomposition of hydrogen peroxide is catalysed by manganese (IV) oxide:2H2O2 (aq) 2H2O (l) + O2 (g)

Table shows the results of an experiment on the decomposition of 50.0 cm3 of hydrogen peroxide catalysed by 0.5 g of manganese(IV) oxide.

Time(s) 0 5 10 15 30 50 75 100 120 140Total volume of O2 (cm3)

0 16 27 36 53 67 79 84 86 86

(a) Plot a graph of volume of oxygen against time. [2 marks]

(b) Why the readings were not taken after 140 seconds.

………………………………………………………………………………………[1 mark]

(c) Based on you graph in (a), calculate(i) the average rate of reaction in the first 40 seconds.

[2 mark]

(ii) The rate of reaction at 50th second.

[2 marks]

(ii) The average rate of the reaction of the experiment.

[2 marks]

(d) Calculate the concentration of hydrogen peroxide used in this experiment.[Molar volume = 22400 cm3 mol-1 at room condition]

[3 marks](e) Suggest one method that can speed up the decomposition of hydrogen

peroxide in the experiment.

………………………………………………………………………………………[1 marks]

(f) Explain you suggestion in (e) using collision theory.

………………………………………………………………………………………

……………………………………………………………………………………… [2 marks]

Answers1. D2. C3. B4. D5. A6. D7. D8. B9. B10. A