Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Electrolysis
198 practice questions
Topics covered
- Why things conduct electricity17 practice questions
- Passing electricity through compounds: electrolysis20 practice questions
- The electrolysis of molten compounds19 practice questions
- Electrolysis and redox19 practice questions
- The electrolysis of other molten substances19 practice questions
- The electrolysis of aqueous solutions18 practice questions
- The electrolysis of sodium chloride solution19 practice questions
- The electrolysis of copper(ii) sulfate solution using inert electrodes18 practice questions
- The electrolysis of some other solutions using inert electrodes19 practice questions
- What would happen with non-electrolytes?19 practice questions
Practice questions
51–60 of 85 · Normal
Question 51
4 marks · Normal
Answer and see the solution →In the electrolysis of sodium chloride solution, hydrogen gas forms at the cathode.
(a)[1 mark]State the ions present in sodium chloride solution that move to the cathode.
(b)[2 marks]Write a balanced half-equation to show the reaction occurring at the cathode. (You may use either half-equation involving H+ or H2O.)
(c)[1 mark]Explain, in one sentence, what happens to the electrons at the cathode during this reaction.
Question 52
3 marks · Normal
Answer and see the solution →During the electrolysis of sodium chloride solution, 0.1 mol of hydrogen gas is collected at the cathode.
Calculate the number of moles of hydroxide ions formed around the cathode by the time this hydrogen gas is collected.
Assume the half-equation at the cathode is:
Question 53
3 marks · Normal
Answer and see the solution →After setting up an electrolytic cell with sodium chloride solution, a student predicts sodium metal will be produced at the cathode.
Use your knowledge of reactivity and the process of electrolysis to explain why this prediction is incorrect.
Question 54
4 marks · Normal
Answer and see the solution →The table shows some possible half-equations for reduction at the cathode during the electrolysis of aqueous sodium chloride.
(a)[2 marks]Possible cathode half-equations Equation Product formed at cathode 2Na^+(aq) + 2e^- → 2Na(s) 2H^+(aq) + 2e^- → H2(g) 2H2O(l) + 2e^- → H2(g) + 2OH^-(aq) (b)[2 marks]Identify which equation(s) correctly represent the cathode reaction for the electrolysis of sodium chloride solution and explain your choice.
Question 55
1 mark · Normal
Answer and see the solution →During the electrolysis of sodium chloride solution, why does the solution near the cathode become alkaline?
- A.Hydrogen gas dissolves to form alkali.
- B.Sodium ions react with water to make sodium hydroxide.
- C.Hydroxide ions are produced at the cathode.
- D.Chlorine neutralises acid at the cathode.
Question 56
2 marks · Normal
Answer and see the solution →State two reasons why hydrogen is produced at the cathode, and not sodium, in the electrolysis of sodium chloride solution.
Question 57
4 marks · Normal
Answer and see the solution →Here are two possible half-equations for a reaction occurring at the cathode during electrolysis of sodium chloride solution:
(a)[1 mark]Name all ions present in the solution that could be reduced at the cathode.
(b)[2 marks]Which of the two half-equations shows the production of hydrogen gas from water? Explain your answer.
(c)[1 mark]Write a word equation for the cathode reaction using water as the starting material.
Question 58
2 marks · Normal
Answer and see the solution →State the products formed at the cathode and at the anode during the electrolysis of copper(II) sulfate solution using inert electrodes.
Question 59
4 marks · Normal
Answer and see the solution →Copper(II) sulfate solution is electrolysed using inert electrodes.
(a)[2 marks]Write the balanced half-equation for the reaction at the cathode.
(b)[2 marks]Write the balanced half-equation for the reaction at the anode.
Question 60
3 marks · Normal
Answer and see the solution →Copper is deposited at the cathode during the electrolysis of copper(II) sulfate solution with inert electrodes.