Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Reversible Reactions and Equilibria
144 practice questions
Topics covered
- Reversibility and dynamic equilibria19 practice questions
- Reversible reactions in a sealed container18 practice questions
- The position of equilibrium20 practice questions
- Changing the pressure19 practice questions
- Changing the temperature19 practice questions
- Adding a catalyst19 practice questions
- The effect of concentration19 practice questions
Practice questions
11–20 of 24 · Hard
Question 11
5 marks · Hard
Answer and see the solution →The equation for a reaction that reaches equilibrium in a sealed container is:
A student investigates how changing the pressure affects this equilibrium.
(a)[1 mark]State the total number of moles of gaseous molecules on each side of the equation.
(b)[2 marks]Predict, with a reason, what will happen to the position of equilibrium if the pressure in the container is increased.
(c)[2 marks]If the pressure is decreased, which side of the equilibrium will be favoured? Explain your answer.
Question 12
2 marks · Hard
Answer and see the solution →Explain, using the idea of gaseous molecules, why changing the pressure does not influence the equilibrium position in reactions involving only solids and liquids.
Question 13
2 marks · Hard
Answer and see the solution →A reversible reaction is at equilibrium. The forward reaction is exothermic. Explain what happens to the position of equilibrium if the temperature is increased.
Question 14
5 marks · Hard
Answer and see the solution →The following reversible reaction is at equilibrium:
(a)[2 marks]State whether the forward reaction is exothermic or endothermic. Explain how you know.
(b)[3 marks]If the position of equilibrium shifts to the right when the temperature is changed, is the temperature being increased or decreased? Explain your reasoning using the ΔH value.
Question 15
2 marks · Hard
Answer and see the solution →For the following equilibrium reaction:
State how increasing the temperature will affect the position of equilibrium. Give your answer for both cases: (i) forward reaction is exothermic; (ii) forward reaction is endothermic.
Question 16
2 marks · Hard
Answer and see the solution →A chemist adds a catalyst to a reversible reaction mixture at equilibrium. The student expects the concentration of products to increase once the catalyst is added.
Explain, with a reason, whether the student's expectation is correct.
Question 17
5 marks · Hard
Answer and see the solution →A student investigates the following reversible reaction at equilibrium: \[ \ce{CO(g) + H2O(g) \rightleftharpoons CO2(g) + H2(g)} \] The student adds a catalyst to the closed reaction vessel.
(a)State what happens to: (i) the rate at which equilibrium is reached (ii) the position of equilibrium after the catalyst is added.
(i)[1 mark]the rate at which equilibrium is reached
(ii)[1 mark]the position of equilibrium
(b)[3 marks]Explain, with reasons, why a catalyst does or does not affect the position of equilibrium in a reversible reaction. Include reference to the rates of the forward and reverse reactions in your answer.
Question 18
2 marks · Hard
Answer and see the solution →Explain why the addition of a catalyst does not affect the position of equilibrium in a reversible reaction.
Question 19
2 marks · Hard
Answer and see the solution →The following reversible reaction is at equilibrium in a sealed container:
State and explain the effect on the position of equilibrium if additional Y(g) is added to the system.
Question 20
5 marks · Hard
Answer and see the solution →The reaction below is at equilibrium in a closed vessel:
A student increases the concentration of P(g).
(a)[1 mark]Predict the effect on the position of equilibrium. State your answer as 'left', 'right' or 'no change'.
(b)[2 marks]Explain your answer in (a), referring to the effect of changing concentration.
(c)[2 marks]If instead some M(g) is removed from the vessel, what effect would this have on the equilibrium position? State your answer and explain.