14.55 B

[Michelle Dong 1F]

A 1.0 m NiSO4(aq) solution was electrolyzed by using inert electrodes. Write (a) the cathode reaction; (b) the anode reaction. (c) With no overpotential or passivity at the electrodes, what is the minimum potential that must be supplied to the cell for the onset of electrolysis?

How do you know the anode reaction is the reduction reaction for water?

[Suchita 2I]

Although the negative ion present in the solution is the SO4 2- ion, which will thus move towards the positive anode, the sulfate ion cannot be oxidized so the oxidation of water takes place, leading to oxygen gas being evolved. However, the reduction half reactions and their standard potentials are given as a convention even though reduction does not take place at the anode.