Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Reversibility and dynamic equilibria
19 practice questions
Practice questions
11–19 of 19
Question 11
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 12
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 13
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 14
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 15
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 16
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 17
2 marks · Hard
Answer and see the solution →Explain, in terms of particle behaviour, why the concentrations of reactants and products remain constant in a sealed container when a reversible reaction has reached dynamic equilibrium.
Question 18
5 marks · Hard
Answer and see the solution →A reversible reaction between gases takes place in a sealed container.
(a)[2 marks]State two characteristics of the system when it has reached dynamic equilibrium.
(b)[3 marks]Explain what would happen to the amount of if the pressure on the system is increased, and relate your answer to the number of moles of gas on each side of the equation.
Question 19
2 marks · Hard
Answer and see the solution →Write a balanced symbol equation for the reversible thermal decomposition of ammonium chloride, including the correct symbol for a reversible reaction.