## 6O1

JChen_2I
Posts: 107
Joined: Fri Aug 09, 2019 12:17 am

### 6O1

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 at the electrodes, what is the minimum potential that must be supplied to the cell for the onset of electrolysis?

How do you find the minimum potential? The solution manual uses 2H2O->O2 +4H+ +4e- (E=+1.23) as the anode reaction. Why would you not use 2H2O +2e- -> H2 + 2OH- (E=-0.42)?

Alex Chen 2L
Posts: 86
Joined: Wed Sep 18, 2019 12:21 am

### Re: 6O1

In electrolysis, you are trying to produce solid, neutral Ni from its ion form as Ni2+ in NiSO4(aq). To do this, you will need to supply electrons from water to reduce the Nickel ions (water is oxidized and electrons are in the products of the half-reaction), which becomes the anode reaction. Therefore Ecell is the standard E of the cathode (nickel) minus the anode (water), -0.23 - (1.23) = -1.46V. Since the Ecell is negative as a result and unfavorable in that direction, the minimum potential required to drive the reaction is the amount of volts added to make Ecell zero (or simply negative Ecell).