CH-1817

Half-equations

Chemistry · Secondary 4 · Medium · Half-equations

A student electrolyses aqueous copper(II) sulfate using a copper anode and a carbon cathode.
Which half‑equation correctly represents the reaction at the copper anode?

$\text{Cu} \rightarrow \text{Cu}^{2+} + 2e^-$
$\text{Cu}^{2+} + 2e^- \rightarrow \text{Cu}$
$2\text{H}_2\text{O} + 2e^- \rightarrow \text{H}_2 + 2\text{OH}^-$
$4\text{OH}^- \rightarrow 2\text{H}_2\text{O} + \text{O}_2 + 4e^-$

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