Q21.86P - Chemistry: Molecular Nature Of Matter And Change

Question

How does over voltage influence the products in the electrolysis of aqueous salts?

Step-by-Step Solution

Answer

Instead of the expected result from the metals in the solutions, overvoltage causes the reaction to produce  ${\text{H}}_{\text{2}}{\text{ or O}}_{\text{2}}$ .

Step 1:

Overvoltage causes the production of ${\text{H}}_{\text{2}}{\text{ or O}}_{\text{2}}$ from the reaction, since there is additional  $0.4-0.6 \text{V}$ applied in the reaction. Overvoltage arises from kinetic factors, where there is a large activation energy needed to be overcome to produce gases in the electrodes.

Hence Overvoltage causes the production of ${\text{H}}_{\text{2}}{\text{ or O}}_{\text{2}}$  from the reaction, instead of just the predicted product from the metals in the solutions.