Question

One of the methods for the manufacture of $H_2{O}_2$ involves electrolysis of:

• A. Concentrated $H_{2}S{O}_4$
• B. An alkaline solution
• C. Concentrated $HCl$
• D. $50\%H_{2}S{O}_4$

Answer 1

The correct option is D $50\%H_{2}S{O}_4$

$H_2{O}_2$ is prepared commercially by electrolysis of $50\%H_{2}S{O}_4$.
Here, the $H_{2}S{O}_4$ is electrolysed to $H_2{S}_2{O}_8$ and then it is hydrolysed to get $H_{2}S{O}_4\text{and}{H}_2{O}_2$
Reactions at Cathode:
$2H^{+}+2e^{-}\to H_2$
Reaction at anode:
$2HS{O}_4^{-}\to H_2{S}_2{O}_8+e^{-}$
Hydrolysis of $H_2{S}_2{O}_8$:
$H_2{S}_2{O}_8+H_{2}O\to H_{2}S{O}_5+H_{2}S{O}_4$
$H_{2}S{O}_5+H_{2}O\to H_{2}S{O}_4+H_2{O}_2$