MHT CET · Chemistry · Electrochemistry

Which among the following is correct for electrolysis of brine solution?

A $O_{2}$ gas is liberated at cathode
B Sodium metal is collected at anode
C $H_{2}$ gas is liberated at cathode
D $C l_{2}$ gas is liberated at cathode

Verified Solution

Answer & Solution

Correct Answer

(C) $H_{2}$ gas is liberated at cathode

Step-by-step Solution

Detailed explanation

In electrolysis of brine solution,

H_{2}

gas is liberated at cathode. The solution contains four ions

N a^{+}, C l^{θ}, H^{+}

and

\overset{θ}{O} H

ions. There occurs a race amongst them for their discharge at their respective electrodes.
Following electrode reactions are possible:

C a t h o d e 2 H_{2} O (l) + 2 e^{-} \to H_{2} (g) + 2 \bar{O} H (a q)

A n o d e 2 C l^{-} (a q) \to C l_{2} (g) + 2 e^{-}

In this electrolysis,

H_{2}

at cathode and

C l_{2}

at anode are given off.

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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