Question

Why are E half-cell values for the oxidation and reduction of water different from E° half-cell values for the same processes? In an aqueous electrolytic cell, nitrate ions never react at the anode, but nitrite ions do. Explain.

Short answer

Because the concentrations of and in solution are varied from the conventional value of$1.0\text{M}$.

Step-by-step solution

Step 1:

The values for oxidation and reduction of water are different from the standard value for the process.

Because of the different concentration of ${\text{H}}^{\text{+}}$and${\text{OH}}^{\text{-}}$in solution, compared to the standard value of$1.0\text{M}$.