Question

Acidified KMnO₄ oxidises sulphite to ______.

Options

• \[\ce{S_2O^2-_4}\]

• \[\ce{S_2O^2-_8}\]

• SO₂(g)

• \[\ce{SO^2-_4}\]

Answer 1

Acidified KMnO oxidises sulphite to \[\ce{\mathbf{\underline{SO_4^{2-}}}}\].

Explanation:

Potassium permanganate (KMnO₄) is a strong oxidising agent, especially in an acidic medium. It accepts electrons from the sulphite ion, causing the sulphite (which has sulfur in the +4 oxidation state) to be oxidised to sulphate (where sulfur is in the +6 oxidation state).

\[\ce{5SO^2-_3 + 2MnO^-_4 + 6H+ -> 2Mn^2+ + 3H2O + 5SO^2-_4}\]