Manganate disproportionates in acid: 3MnO4^2- + 4H^+ -> 2MnO4^- + MnO2 + 2H2O. The fraction of the manganate (Mn(VI)) that is oxidised to permanganate is

JEE Advanced levelSingle correct optionDifficulty 3 of 3rx093

Manganate disproportionates in acid: $3 MnO X_{4} X^{2 -} + 4 H X^{+} 2 MnO X_{4} X^{-} + MnO X_{2} + 2 H X_{2} O$ . The fraction of the manganate (Mn(VI)) that is oxidised to permanganate is

Of 3

MnO X_{4} X^{2 -}

, 2 become

MnO X_{4} X^{-}

(+6 to +7, oxidised) and 1 becomes

MnO X_{2}

(+6 to +4, reduced). Electron check: 2 x 1 lost = 1 x 2 gained. The fraction oxidised is 2/3.