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
21–30 of 85 · Normal
Question 21
1 mark · Normal
Answer and check →Which of the following half-equations correctly represents the reaction occurring at the anode during the electrolysis of molten potassium bromide (KBr)?
- A.Br^- → Br_2 + 2e^-
- B.K^+ + e^- → K
- C.2Br^- → Br_2 + 2e^-
- D.K^+ → K + e^-
Question 22
2 marks · Normal
Answer and see the solution →Write the half-equation for the reaction at the cathode during the electrolysis of molten zinc chloride (ZnCl_2). State what is observed at the cathode.
Question 23
4 marks · Normal
Answer and see the solution →The diagram below shows the electrolysis of molten copper(II) bromide (CuBr2) using carbon electrodes.
Apparatus for electrolysis of molten copper(II) bromide. (a)[1 mark]Identify the ions present in molten copper(II) bromide.
(b)[1 mark]State what is produced at the cathode and at the anode.
(c)[1 mark]Write the half-equation for the reaction at the cathode.
(d)[1 mark]Describe a visible change that would be observed at the anode during electrolysis.
Question 24
3 marks · Normal
Answer and see the solution →Molten sodium chloride (NaCl) is electrolysed using inert electrodes.
(a)[1 mark]State the ions present in molten sodium chloride.
(b)[1 mark]Write the balanced half-equation for the reaction at the cathode.
(c)[1 mark]Identify the product formed at the anode and write the half-equation for its formation.
Question 25
3 marks · Normal
Answer and see the solution →Electrolysis is carried out on molten magnesium chloride (MgCl2) using inert electrodes.
(a)[1 mark]Predict the product formed at the anode. Explain your answer.
(b)[1 mark]Write a balanced half-equation for the reaction at the cathode.
(c)[1 mark]Explain why molten magnesium chloride conducts electricity, but solid magnesium chloride does not.
Question 26
2 marks · Normal
Answer and see the solution →State what is meant by:
(a)[1 mark]oxidation, in terms of electron transfer.
(b)[1 mark]reduction, in terms of electron transfer.
Question 27
4 marks · Normal
Answer and see the solution →The diagram shows an apparatus used in the electrolysis of molten lead(II) iodide. The electrodes and power supply are labelled.
(a)[2 marks]Explain what is meant by 'discharging an ion' during electrolysis.
(b)[1 mark]State what happens to the lead(II) ions at the cathode, referring to electron transfer.
(c)[1 mark]Write the ionic half-equation for the reaction at the anode.
Question 28
3 marks · Normal
Answer and see the solution →The electrolysis of molten potassium chloride (KCl) produces potassium metal and chlorine gas.
(a)[1 mark]Write the half-equation for the reaction at the cathode.
(b)[1 mark]State whether the reaction at the cathode is oxidation or reduction.
(c)[1 mark]Explain your answer to part (b) in terms of electron transfer.
Question 29
3 marks · Normal
Answer and see the solution →A student wants to remember whether oxidation or reduction involves losing or gaining electrons.
(a)[1 mark]State the mnemonic used to remember this.
(b)[1 mark]What does each letter in the mnemonic stand for?
(c)[1 mark]Explain, using the mnemonic, what happens to an ion that gains electrons.
Question 30
4 marks · Normal
Answer and see the solution →Table 1: Electrode Reactions Ion Half-equation Cl^- 2Cl^- \rightarrow Cl_2 + 2e^- Ag^+ Ag^+ + e^- \rightarrow Ag Fe^{3+} Fe^{3+} + 3e^- \rightarrow Fe O^{2-} 2O^{2-} \rightarrow O_2 + 4e^- Study Table 1. For each reaction below, state whether the ion is oxidised or reduced and explain why using electron transfer.
(a)[1 mark]Cl^- \rightarrow Cl_2 + 2e^-
(b)[1 mark]Ag^+ + e^- \rightarrow Ag
(c)[1 mark]Fe^{3+} + 3e^- \rightarrow Fe
(d)[1 mark]O^{2-} \rightarrow O_2 + 4e^-