The electrolysis of copper(ii) sulfate solution using inert electrodes
2 marks · EasyThe reactivity series places copper below hydrogen. Using this fact and your knowledge of ions in copper(II) sulfate solution, explain why copper is deposited at the cathode and not hydrogen during electrolysis with inert electrodes.
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Copper ions are below hydrogen in the reactivity series, so copper(II) ions are more easily reduced than hydrogen ions and are deposited at the cathode.
Must show: Reference to reactivity series, Copper ions more easily reduced/gain electrons than hydrogen ions
Also accept: Copper ions are discharged in preference to hydrogen ions because copper is less reactive.
Common mistakes: Saying hydrogen is less reactive; Not mentioning reactivity series
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Marking points
M1 · 1 mark · Mentions that copper is below hydrogen in the reactivity series (or less reactive than hydrogen).
M1 · 1 mark · States that copper(II) ions are preferentially reduced/deposited at the cathode instead of hydrogen ions.
Worked solution
Copper is below hydrogen in the reactivity series. Therefore, copper(II) ions are more easily reduced (gain electrons) at the cathode than hydrogen ions, so copper is deposited and hydrogen is not.