Senior Secondary (HKDSE) · Chemistry

Collision theory, activation energy, catalysts: Practice Questions

5 multiple-choice questions marked as you go, and 2 written questions with worked solutions. All on Collision theory, activation energy, catalysts.

7 questions14 marksFree, no account

Question 1

1 mark

Breaking a large piece of calcium carbonate into smaller chips increases its reaction rate with dilute hydrochloric acid. According to collision theory, this is because:

Question 2

1 mark

The diagram below shows the energy profile for a chemical reaction. Which of the following changes would occur if a suitable catalyst is introduced to the system?

I. The enthalpy change of the reaction (\(\Delta H\)) will decrease.
II. The activation energy for the forward reaction will decrease.
III. The activation energy for the backward reaction will decrease by the same amount as the forward reaction.

Question 3

1 mark

According to the collision theory, which of the following statements best explains why doubling the concentration of a gaseous reactant at constant temperature increases the reaction rate?

Question 4

1 mark

Which of the following statements about a catalyst is correct?

Question 5

1 mark

When the temperature of a reaction mixture is increased, the rate of reaction increases significantly. Which of the following is the most important factor contributing to this increase according to collision theory?

Question 6

3 marks

In terms of collision theory, explain how a heterogeneous catalyst, such as finely divided iron used in the Haber process, increases the rate of the reaction between nitrogen and hydrogen gas.

Write your answer out first, then check it against the worked solution.

Question 7

6 marks

Using collision theory and the concept of activation energy, explain why a catalyst increases the rate of both the forward and reverse reactions equally, and thus does not affect the position of chemical equilibrium.

Write your answer out first, then check it against the worked solution.

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