In experiment 1, aqueous copper(II) sulfate is electrolysed with graphite electrodes. In experiment 2, aqueous copper(II) sulfate is electrolysed with copper electrodes. Which statement identifies a half-equation for a reaction at one of the electrodes?
- AIn experiment 1, the half-equation for the anode reaction is $4\text{OH}^- \rightarrow 2\text{H}_2\text{O} + \text{O}_2 + 4e^-.$
- BIn experiment 1, the half-equation for the cathode reaction is $2\text{H}^+ + 2e^- \rightarrow \text{H}_2.$
- CIn experiment 2, the half-equation for the anode reaction is $\text{Cu}^{2+} + 2e^- \rightarrow \text{Cu}.$
- DIn experiment 2, the half-equation for the cathode reaction is $4\text{OH}^- \rightarrow 2\text{H}_2\text{O} + \text{O}_2 + 4e^-.$