Question

Which of the following electrolyte can be used to obtain \( \text{H}_2\text{S}_2\text{O}_8 \) by the process of electrolysis?

• A. Dilute solution of sodium sulphate
• B. Dilute solution of sulphuric acid
• C. Concentrated solution of sulphuric acid
• D. Acidified dilute solution of sodium sulphate

Hint:

To produce peroxydisulfuric acid (\( \text{H}_2\text{S}_2\text{O}_8 \)), concentrated sulfuric acid is used in the electrolysis process.

Answer 1

The Correct Option is C

To determine which electrolyte can be used to obtain \( \text{H}_2\text{S}_2\text{O}_8 \) (peroxydisulfuric acid) by the process of electrolysis, we need to understand the conditions required for its formation:

1. Principle of Electrolysis: Electrolysis involves the decomposition of compounds using an electric current. The electrolyte's nature significantly affects the products formed.

2. Peroxydisulfuric Acid Formation: This compound is specifically formed when concentrated sulfuric acid is electrolyzed. The equation for the formation of \( \text{H}_2\text{S}_2\text{O}_8 \) is as follows:

2 \( \text{HSO}_4^- \) (aq) → \( \text{H}_2\text{S}_2\text{O}_8 \) (aq) + 2 \( e^- \)

3. Options Analysis:

Option	Suitability
Dilute solution of sodium sulphate	Not suitable, lacks sufficient sulfate ions and concentration.
Dilute solution of sulphuric acid	Not suitable due to low concentration.
Concentrated solution of sulphuric acid	Suitable; provides high concentration of sulfate ions for forming \( \text{H}_2\text{S}_2\text{O}_8 \).
Acidified dilute solution of sodium sulphate	Not suitable, lacks adequate concentration of \( \text{HSO}_4^- \) ions.

The process's efficiency in forming \( \text{H}_2\text{S}_2\text{O}_8 \) increases with the concentration of \( \text{HSO}_4^- \) ions provided by concentrated sulfuric acid, which makes it the correct choice.