Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Changing the temperature
19 practice questions
Practice questions
11–19 of 19
Question 11
3 marks · Normal
Answer and see the solution →A reversible reaction is shown below.
Calculate the enthalpy change (ΔH) for the reverse reaction. State whether the reverse reaction is exothermic or endothermic.
Question 12
3 marks · Normal
Answer and see the solution →The reaction below reaches equilibrium at a certain temperature:
Explain what will happen to the position of equilibrium if you decrease the temperature. Refer to the direction of the equilibrium shift.
Question 13
4 marks · Normal
Answer and see the solution →The table below shows the percentage of X and Y at equilibrium for a reversible reaction at two temperatures.
Temperature (°C) % X at equilibrium % Y at equilibrium 350 30 70 150 65 35 (a)[1 mark]Describe how the percentage of X changes as temperature decreases.
(b)[2 marks]Which direction of reaction is favoured at lower temperature? Explain your answer using the data.
(c)[1 mark]State whether the formation of X from Y is likely exothermic or endothermic. Give a reason.
Question 14
1 mark · Normal
Answer and check →Which statement about ΔH for a reversible reaction is correct?
- A.ΔH always refers to the forward reaction.
- B.ΔH is positive for all exothermic reactions.
- C.ΔH is the same for both directions of the reaction.
- D.ΔH is only given for endothermic reactions.
Question 15
2 marks · Normal
Answer and see the solution →Explain what happens to the position of equilibrium when temperature is increased in a reversible reaction.
Question 16
4 marks · Normal
Answer and see the solution →The equation below shows a reversible reaction.
(a)[1 mark]Is the forward reaction exothermic or endothermic? Explain your answer.
(b)[2 marks]Predict what happens to the position of equilibrium if the temperature is decreased. Explain your answer.
(c)[1 mark]Which direction (left or right) is favoured when temperature is increased? Explain.
Question 17
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 18
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 19
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.