Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Reversible reactions in a sealed container
18 practice questions
Practice questions
1–8 of 8 · Normal
Question 1
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 2
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.
Question 3
3 marks · Normal
Answer and see the solution →Explain, with reasons, why a sealed container is necessary for studying reversible reactions.
Question 4
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 5
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 6
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 7
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 8
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.