Aqueous copper chloride solution is electrolysed using inert electrodes. Describe and explain what is produced at each electrode, naming the electrode in each case.

Edexcel GCSE Chemistry (1CH0) — 3.2 Electrolytic processes · Describe and explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

At the anode (positive electrode) chloride ions are oxidised:

Cl⁻ → ½Cl₂(g) + e⁻

Chlorine gas is released. At the cathode (negative electrode) copper ions are reduced:

Cu²⁺ + 2e⁻ → Cu(s)

Copper metal is deposited on the cathode.

Examiner tips

  • Use the correct electrode names (anode, cathode) and state the reaction direction (oxidation/reduction).
  • Show the half‑reactions to justify why Cl₂ and Cu are produced.
  • Mention that hydrogen evolution is suppressed because Cu²⁺ is reduced first.

Common mistakes

  • Confusing anode with cathode or vice versa.
  • Writing oxygen evolution at the anode instead of chlorine.

Mark scheme (4 marks)

  1. Chlorine is produced at the anode (positive electrode)
  2. At the anode, chloride ions lose electrons (oxidation), so chlorine is produced rather than oxygen because the solution contains halide ions
  3. Copper is produced at the cathode (negative electrode)
  4. At the cathode, copper ions gain electrons (reduction), so copper is deposited rather than hydrogen because copper is less reactive than hydrogen

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