Question

Discuss in detail the oxidising character of potassium permanganate in acidic solutions. Give at least two reactions in the given case.

Answer 1

In an acidic medium, potassium permanganate functions as a strong oxidizing agent. It reacts as follows when diluted sulphuric acid is present.

\[\ce{2KMnO4 + 3H2SO4 -> K2SO4 + 2MnSO4 + 3H2O + 5O}\]

The reaction actually involves the reduction of MnO₄ ions to Mn²⁺ ions.

\[\ce{MnO^-_4 + 8H+ + 5e- -> Mn^{2+} + 4H2O}\]

KMnO₄ acts as a potent oxidizing agent in an acidic medium because of the higher standard potential value that corresponds to the reduction of \[\ce{MnO^-_4}\] ions to Mn²⁺ ions. Also, the equivalent mass of KMnO₄ in an acidic medium is one-fifth of its molecular mass since the reaction requires five moles of electrons for every mole of MnO₄ ions. KMnO₄ is largely used as an oxidising agent in an acidic medium.