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
1–10 of 63 · Normal
Question 1
2 marks · Normal
Answer and see the solution →Hydrated cobalt(II) chloride can be heated to produce anhydrous cobalt(II) chloride and water. The process is reversible.
State the chemical equation for this reversible reaction, using the correct symbol, and explain what the symbol means.
Question 2
4 marks · Normal
Answer and see the solution →The reversible reaction between hydrogen and iodine to form hydrogen iodide can reach dynamic equilibrium in a sealed tube.
(a)[2 marks]State what is meant by dynamic equilibrium.
(b)[2 marks]Describe two conditions necessary for dynamic equilibrium to occur in this reaction.
Question 3
3 marks · Normal
Answer and see the solution →At dynamic equilibrium in a sealed vessel, the following reversible reaction occurs:
Suppose the rate of the forward reaction is 0.160 mol dm⁻³ min⁻¹ when equilibrium is reached. Calculate:
(a)[1 mark]The rate of the reverse reaction at equilibrium.
(b)[2 marks]If 0.160 mol of N2O4 is used up in 1 minute, how much NO2 would be produced in that time by the forward reaction?
Question 4
3 marks · Normal
Answer and see the solution →Some students write the following equation:
Explain how you could tell whether this reaction is reversible or not, using the chemical symbols and the reaction itself.
Question 5
4 marks · Normal
Answer and see the solution →The table shows the concentration of hydrogen, iodine and hydrogen iodide in a sealed container at different times during a reversible reaction.
Time (min) [H2] (mol dm⁻³) [I2] (mol dm⁻³) [HI] (mol dm⁻³) 0 0.50 0.50 0.00 1 0.30 0.30 0.40 2 0.21 0.19 0.60 3 0.19 0.18 0.64 4 0.18 0.17 0.65 5 0.18 0.17 0.65 Use the data to answer the following questions.
(a)[2 marks]At what time does the reaction reach dynamic equilibrium? Explain how you know.
(b)[1 mark]State one characteristic of the reaction mixture at equilibrium based on the data.
(c)[1 mark]Suggest what would happen if more H2 is added at equilibrium.
Question 6
2 marks · Normal
Answer and see the solution →Ammonium chloride can decompose when heated to form ammonia and hydrogen chloride. The reaction is reversible.
Write a balanced chemical equation for this reaction, including the correct symbol for reversibility, and name one characteristic of a reversible reaction.
Question 7
4 marks · Normal
Answer and see the solution →The reversible decomposition of dinitrogen tetroxide to nitrogen dioxide is shown below:
(a)[2 marks]Explain what is meant by 'dynamic' in dynamic equilibrium.
(b)[2 marks]Describe what you would observe in the sealed container when equilibrium has been reached.
Question 8
1 mark · Normal
Answer and check →Which statement correctly describes the characteristics of a reaction at dynamic equilibrium in a sealed container?
- A.The forward reaction has stopped, but the reverse reaction continues.
- B.The concentrations of reactants and products do not change because both reactions have stopped.
- C.The forward and reverse reactions continue at the same rate, and concentrations of all substances stay constant.
- D.The amount of reactants decreases steadily until only products remain.
Question 9
2 marks · Normal
Answer and see the solution →State what is meant by a sealed container in the context of reversible reactions. Give two essential features.
Question 10
4 marks · Normal
Answer and see the solution →A reversible reaction takes place in a sealed flask. At first, only reactants are present. The forward reaction starts quickly, but slows down over time.
(a)[1 mark]Explain why the rate of the forward reaction decreases as the reaction proceeds.
(b)[1 mark]Describe what is happening with the reverse reaction as the products begin to form.
(c)[1 mark]State what is meant by equilibrium in this context.
(d)[1 mark]Explain why equilibrium can only be reached in a sealed container.