JEE Main · 2023 · 30 Jan 2023 · Shift 1 · d and f Block Elements

The number of electrons involved in the reduction of permanganate to manganese dioxide in acidic medium is ______.

Answer: 3

Solution

In acidic solution the permanganate ion is reduced to manganese dioxide, the manganese dropping from the

+ 7

state in

Mn O_{4}^{-}

to the

+ 4

state in

Mn O_{2}

. Balancing the half-reaction gives

Mn O_{4}^{-} + 4 H^{+} + 3 e^{-} \to Mn O_{2} + 2 H_{2} O

. The change of three units in oxidation state means three electrons are gained, so the number of electrons involved is

3

JEE Main · 2023 · 30 Jan 2023 · Shift 1 · Integer answer