Question

Which of the following reactions takes place at anode during the electrolysis of molten NaCl?

• A. \(\text{Na}_{(l)}^++\text{e}^-\rightarrow \text{Na}_{(l)}\)
• B. \(\text{Na}_{(s)}\rightarrow \text{Na}_{(l)}^++\text{e}^-\)
• C. \(\text{Cl}_{2(g)}+2\text{e}^-\rightarrow 2\text{Cl}_{(l)}^-\)
• D. \(2\text{Cl}_{(l)}^-\rightarrow \text{Cl}_{2(g)}+2\text{e}^-\)

Hint:

Oxidation takes place at the anode, so chloride ions lose electrons.

Answer 1

The Correct Option is D

Step 1: Recall the rule
At the anode oxidation occurs, which means a species loses electrons.

Step 2: Ions present
Molten NaCl has \(Na^+\) and \(Cl^-\). Only \(Cl^-\) can lose electrons: \(2Cl^-_{(l)} \rightarrow Cl_{2(g)} + 2e^-\).

Step 3: Why others are wrong
(A) is reduction of \(Na^+\) at the cathode. (B) is not the reaction in the cell, since solid sodium is not at the anode. (C) is the reverse of (D) and is a reduction.

Final Answer:
Chloride ions are oxidised at the anode. \[ \boxed{\text{(D)}\ 2Cl^-_{(l)} \rightarrow Cl_{2(g)} + 2e^-} \]