Question

Acidified \(KMnO_4\) oxidizes sulphite to: 

• A. \(SO_3^{2-} \)
• B. \(SO_4^{2-} \)
• C. \(SO_2(g) \)
• D. \(S_2O_8^{2-} \)

Hint:

KMnO_4 in acidic conditions oxidizes sulphite to sulfate.

Answer 1

The Correct Option is D

Solution:

The interaction between acidified potassium permanganate (KMnO₄) and sulphite (SO₃^2-) is an oxidation-reduction (redox) reaction. In this process, KMnO₄ functions as an oxidizing agent, transforming the sulphite ion.

Sulphur in SO₃^2- has an oxidation state of +4. The oxidation process aims to elevate this oxidation state. Acidified KMnO₄ oxidizes sulphite ions to peroxodisulfate ions (S₂O₈^2-). This results in a compound with two sulphur atoms linked by an oxygen-oxygen bond, each sulphur atom exhibiting a +6 oxidation state.

The balanced redox equation is:

2KMnO₄ + 5SO₃^2- + 6H⁺ → 2Mn²⁺ + 5SO₄^2- + 3H₂O

Correct answer:

S₂O₈^2-