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
31–40 of 85 · Normal
Question 31
1 mark · Normal
Answer and check →In the electrolysis of molten zinc bromide, what does it mean to 'discharge' a zinc ion (Zn^{2+}) at the cathode?
- A.Zinc ions lose electrons to form zinc atoms.
- B.Zinc ions gain electrons to form zinc atoms.
- C.Zinc atoms lose electrons to form zinc ions.
- D.Zinc ions are removed from the solution by evaporation.
Question 32
2 marks · Normal
Answer and see the solution →For the electrolysis of molten calcium bromide (CaBr_2):
(a)[1 mark]Which electrode (anode or cathode) is the site of oxidation?
(b)[1 mark]Which electrode reaction involves reduction?
Question 33
4 marks · Normal
Answer and see the solution →You are asked to explain how the OILRIG mnemonic helps when deciding whether a reaction is oxidation or reduction.
(a)[2 marks]Write what each letter in OILRIG stands for.
(b)[1 mark]Use the mnemonic to decide whether the following process is oxidation or reduction: Fe^{2+} gains 2 electrons to form Fe.
(c)[1 mark]State how the mnemonic helps you to answer part (b).
Question 34
2 marks · Normal
Answer and see the solution →Write the ionic half-equations for the electrolysis of molten magnesium chloride. Identify which half-equation is for the cathode and which is for the anode.
Question 35
4 marks · Normal
Answer and see the solution →This question is about the electrolysis of molten lead(II) bromide.
(a)[2 marks]Write the balanced ionic half-equation for the reaction at the cathode.
(b)[2 marks]Write the balanced ionic half-equation for the reaction at the anode.
Question 36
3 marks · Normal
Answer and see the solution →A chemist electrolyses molten potassium iodide (KI).
Predict which element is formed at (a) the cathode and (b) the anode. Explain your reasoning in each case.
Question 37
3 marks · Normal
Answer and see the solution →During the electrolysis of molten aluminium oxide, explain how you can check that each ionic half-equation is correctly balanced. Include checks for both the numbers of atoms and the charges.
Question 38
4 marks · Normal
Answer and see the solution →Student equations for the electrolysis of molten calcium bromide Student Cathode equation Anode equation A Ca^{2+} + 2e^- \to Ca 2Br^- \to Br_2 + 2e^- B Ca^{2+} \to Ca + 2e^- Br^- \to Br_2 + 2e^- C Ca^{2+} + e^- \to Ca 2Br^- \to Br_2 + 2e^- D Ca^{2+} + 2e^- \to Ca 2Br^- \to Br_2 + e^- Use the table above. For each equation below, state which students wrote it correctly. For each incorrect equation, explain the mistake.
Question 39
1 mark · Normal
Answer and check →Which element forms at the anode during the electrolysis of molten sodium bromide (NaBr)?
- A.Bromine
- B.Sodium
- C.Hydrogen
- D.Oxygen
Question 40
2 marks · Normal
Answer and see the solution →Complete the ionic half-equations for the electrolysis of molten copper(II) bromide. Include state symbols.