Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Adding a catalyst
19 practice questions
Practice questions
1–8 of 8 · Easy
Question 1
1 mark · Easy
Answer and see the solution →State the effect of adding a catalyst on the position of equilibrium in a reversible chemical reaction.
Question 2
3 marks · Easy
Answer and see the solution →(a)A reversible reaction mixture is at equilibrium. A catalyst is added to the system.
Explain what happens to:
(i)[1 mark]the rate at which the equilibrium is reached,
(ii)[1 mark]the position of equilibrium,
(iii)[1 mark]the amount of products at equilibrium.
Question 3
2 marks · Easy
Answer and see the solution →In a reversible reaction at equilibrium, the rate of the forward reaction is 0.6 mol/dm³/s and the rate of the reverse reaction is also 0.6 mol/dm³/s. A catalyst is added and both rates are increased by a factor of 5.
Calculate the new rate of the forward reaction, and state whether the position of equilibrium will change.
Question 4
2 marks · Easy
Answer and see the solution →A student claims that adding a catalyst to a reversible reaction will result in more products being formed at equilibrium. Explain, with reasons, whether the student is correct.
Question 5
3 marks · Easy
Answer and see the solution →The concentrations of reactants and products in a reversible reaction at equilibrium are measured every minute. At minute 4, a catalyst is added. The concentrations at each minute are shown below.
Concentration data (mol/dm³) Time (min) [Reactant] [Product] 0 1.00 0.00 1 0.85 0.15 2 0.75 0.25 3 0.71 0.29 4 0.70 0.30 5 0.70 0.30 6 0.70 0.30 (a)[1 mark]Describe the effect of adding the catalyst on the time taken to reach equilibrium.
(b)[1 mark]Use the data to state the concentrations at equilibrium.
(c)[1 mark]Does adding the catalyst change the equilibrium concentrations? Explain your answer.
Question 6
1 mark · Easy
Answer and see the solution →What does a catalyst do to the rates of the forward and reverse reactions in a reversible process?
Question 7
3 marks · Easy
Answer and see the solution →Nitrogen dioxide, NO₂, and dinitrogen tetroxide, N₂O₄, form a reversible reaction at equilibrium:
(a)[1 mark]State what happens to the colour of the mixture when a catalyst is added.
(b)[1 mark]Explain whether the ratio of NO₂ to N₂O₄ changes after the catalyst is added.
(c)[1 mark]Give a reason for your answer to (b).
Question 8
2 marks · Easy
Answer and see the solution →A reversible reaction reaches equilibrium after 12 minutes. When a catalyst is added, it reaches equilibrium in just 3 minutes. Calculate by what factor the rate of reaching equilibrium has increased. State if the position of equilibrium is affected.