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
131–140 of 144
Question 131
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 132
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.
Question 133
2 marks · Hard
Answer and see the solution →For the equilibrium reaction below:
Explain, in terms of concentration, what happens to the position of equilibrium if some B(g) is removed from the mixture.
Question 134
5 marks · Easy
Answer and see the solution →This question is about reversibility in chemical reactions, especially in sealed containers.
(a)[2 marks]What is meant by a reversible reaction? State the symbol used to represent a reversible reaction in a chemical equation.
(b)Copper(II) sulfate crystals can lose water when heated and regain it when water is added.
(i)[1 mark]Write a balanced chemical equation using symbols to show the reversible change involving hydrated and anhydrous copper(II) sulfate.
(ii)[2 marks]What does it mean if this reaction occurs in a sealed container?
Question 135
5 marks · Easy
Answer and see the solution →This question is about dynamic equilibrium and how it is achieved in sealed containers.
(a)[2 marks]Explain what is meant by dynamic equilibrium in a reversible reaction.
(b)A chemical reaction is happening in a sealed container.
(i)[1 mark]Describe what happens to the concentrations of reactants and products once dynamic equilibrium is reached.
(ii)[2 marks]State the essential feature of the rates of the forward and reverse reactions at equilibrium in a sealed container.
Question 136
5 marks · Easy
Answer and see the solution →Reversible reactions often behave differently in sealed containers. Use your knowledge to answer the following questions.
(a)[2 marks]State one example of a reversible reaction and write its equation using the proper symbol.
(b)[2 marks]Explain why it is important for a container to be sealed when studying the equilibrium of a reversible reaction.
(c)[1 mark]Describe, with reference to sealed containers, how the forward and reverse reactions compare at dynamic equilibrium.
Question 137
6 marks · Normal
Answer and see the solution →This question is about how both the position of equilibrium and changes in pressure affect reversible reactions involving gases.
(a)[2 marks]For the reaction below in a sealed vessel, is dynamic equilibrium reached? Explain your reasoning.
(b)[2 marks]State why changing the pressure only affects the position of equilibrium in reactions with different numbers of gaseous molecules on each side of the equation.
(c)[2 marks]If the pressure is increased in the vessel containing the equilibrium mixture above, state and explain which direction (left or right) the position of equilibrium will shift.
Question 138
6 marks · Normal
Answer and see the solution →Reversible reactions may respond differently to changes in pressure. Consider the information below for the following questions.
Equilibrium mixture at different conditions Condition Percentage of X Percentage of Y At 1 atm 75 25 At 3 atm 85 15 (a)[2 marks]The equilibrium is: State, with a reason, under which condition the position of equilibrium lies further to the right.
(b)[2 marks]Explain why a change in pressure affects the relative percentages of X and Y in this equilibrium.
(c)[2 marks]Predict and explain in which direction (left or right) the equilibrium will shift if the pressure is decreased.
Question 139
6 marks · Normal
Answer and see the solution →The following equation represents a reversible reaction carried out in a sealed container:
(a)[2 marks]State what would happen to the position of equilibrium if the temperature of the system is increased.
(b)[2 marks]Explain why a catalyst does not change the position of equilibrium in this reaction.
(c)[2 marks]The reaction mixture is left for several hours at a constant temperature and with a catalyst present. Would changing the catalyst affect the final amount of SO₃ present at equilibrium? Explain your answer.
Question 140
6 marks · Normal
Answer and see the solution →Hydrogen iodide is formed in a reversible reaction:
(a)[3 marks]Explain, in terms of exothermic and endothermic reactions, what happens to the position of equilibrium if the temperature is decreased.
(b)[3 marks]Explain why adding a catalyst to the sealed reaction vessel does not change the position of equilibrium.