In alkaline medium oxalate is oxidised to carbonate by permanganate, which is reduced to MnO2. The balanced equation (smallest whole numbers) contains OH^- with coefficient

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In alkaline medium oxalate is oxidised to carbonate by permanganate, which is reduced to $MnO X_{2}$ . The balanced equation (smallest whole numbers) contains $OH X^{-}$ with coefficient

Mn gains 3 electrons and each oxalate loses 2, so

MnO X_{4} X^{-}

C X_{2} O X_{4} X^{2 -}

= 2 : 3. Charge on the left is -2 -6 = -8 while the 6 carbonate on the right carry -12, so 4

OH X^{-}

must be added on the left. Balanced:

2 MnO X_{4} X^{-} + 3 C X_{2} O X_{4} X^{2 -} + 4 OH X^{-} 2 MnO X_{2} + 6 CO X_{3} X^{2 -} + 2 H X_{2} O