Consider the reaction below.

2 upper I superscript minus (a q) plus upper C l subscript 2 (g) right arrow 2 upper C l minus (a q) plus upper I subscript 2 (a q).

Which half reaction correctly describes the reduction that is taking place?

The reduction half cell reaction is Cl₂ (g) + 2e⁻ → 2Cl⁻ (aq)

Explanation:

2I⁻ (aq) + Cl₂ (g) → 2Cl⁻ (aq) + I₂ (aq)

This is the given balanced red-ox reaction.

In this reaction, oxidation as well as reduction occurs at the same time. In the oxidation half reaction, there is increase in the oxidation state of an atom. In the reduction half cell reaction, there is decrease in the oxidation state of an atom.

Here, we have to find the reduction half reaction, and here the oxidation state of chlorine atom is decreased from 0 to - 1, whereas in the oxidation half reaction, the oxidation state of Iodine atom is increased from - 1 to 0.

So the reduction half reaction is,

Cl₂ (g) + 2e⁻ → 2Cl⁻ (aq)