JEE Main 2025 Jan 22 Shift 1, Chemistry Q14: Electrolytic Cells And Electrolysis

JEE Main2025Jan 22, Shift 1Chemistry

Which of the following electrolyte can be used to obtain H $_{2}$ S $_{2}$ 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.

Solution

Peroxydisulphuric acid (Marshall's acid), H $_{2}$ S $_{2}$ O $_{8}$ , is prepared industrially by electrolysing concentrated sulphuric acid (or concentrated bisulphate solutions).

At the anode, two HSO $_{4}^{-}$ ions are oxidised and coupled through an O $-$ O bond:

$2 HSO_{4}^{-} \to H_{2} S_{2} O_{8} + 2 e^{-}$ .

Dilute solutions give O $_{2}$ at the anode instead, so concentrated H $_{2}$ SO $_{4}$ is required.

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JEE Main 2025 Jan 22 Shift 1, Chemistry Q14: Electrolytic Cells And Electrolysis

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