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 63 · Normal
Question 11
3 marks · Normal
Answer and see the solution →Explain, with reasons, why a sealed container is necessary for studying reversible reactions.
Question 12
4 marks · Normal
Answer and see the solution →The table shows the number of blue and yellow squares in a sealed container at intervals during a reversible reaction.
Time (s) Number of blue squares Number of yellow squares 0 64 0 1 48 16 2 36 28 3 27 37 4 20 44 (a)[1 mark]Describe the trend in the number of blue squares over time.
(b)[1 mark]Describe how the number of yellow squares changes over time.
(c)[1 mark]Predict what will happen to the numbers of blue and yellow squares if the reaction continues.
(d)[1 mark]Explain how these trends are related to reversible reactions reaching equilibrium.
Question 13
1 mark · Normal
Answer and check →Which process below best describes the decomposition of ammonium chloride, when heated in a sealed container?
- A.NH4Cl(s) breaks down into NH3(g) and HCl(g), which cannot escape and can recombine to form NH4Cl(s).
- B.NH4Cl(s) melts into a liquid and cannot return to solid form.
- C.NH4Cl(s) reacts with oxygen to form water and nitrogen gas.
- D.NH4Cl(s) changes into NH3(g) and HCl(g), which leave the container permanently.
Question 14
2 marks · Normal
Answer and see the solution →State two reasons why no substances can escape from a sealed container during a reversible reaction.
Question 15
4 marks · Normal
Answer and see the solution →A student heats ammonium chloride in a sealed test tube. The following reversible reaction occurs:
Answer the following questions about this experiment.
(a)[1 mark]State what is meant by a sealed container in this experiment.
(b)[1 mark]Describe what happens to NH3 and HCl in the sealed container after heating.
(c)[1 mark]Explain why both the forward and reverse reactions occur in this setup.
(d)[1 mark]Explain how equilibrium is reached during the reaction.
Question 16
3 marks · Normal
Answer and see the solution →A sample of solid ammonium chloride, , is heated in a sealed tube. The decomposition reaction is:
Suppose you start with 0.80 mol of in the tube. After reaching equilibrium, 0.32 mol of remains.
Calculate the amount (in mol) of ammonia gas, , present at equilibrium.
Question 17
4 marks · Normal
Answer and see the solution →Methanol can be produced from carbon monoxide and hydrogen:
This reaction is reversible and carried out in a sealed container.
(a)[2 marks]Explain what happens to the position of equilibrium when the temperature is increased, assuming the forward reaction is exothermic.
(b)[2 marks]Describe how increasing the pressure will affect the position of equilibrium.
Question 18
3 marks · Normal
Answer and see the solution →Ethene (3) reacts reversibly with steam to form ethanol (85):
The forward reaction is exothermic.
Explain, with reasons, the effect of decreasing both temperature and pressure on the yield of ethanol at equilibrium.
Question 19
2 marks · Normal
Answer and see the solution →State and explain what would happen to the position of equilibrium if the pressure is decreased for the following reaction in a sealed container:
Question 20
4 marks · Normal
Answer and see the solution →Ammonia is made in the Haber process:
The forward reaction is exothermic.
(a)[2 marks]Explain what happens to the yield of ammonia if the temperature is increased.
(b)[2 marks]Describe and explain the effect of increasing pressure on the position of equilibrium.