What is meant by 'disproportionation'? Give two examples of disproportionation reaction in aqueous solution.

Explanation

It is found that sometimes a relatively less stable oxidation state undergoes an oxidation­−reduction reaction in which it is simultaneously oxidised and reduced. This is called disproportionation.
For example, `{:((i) , 3CrO_(4)^(3-) + 8H^(+) to 2CrO_(4)^(2-) + Cr^(3+) + 4H_(2)O) , (,""Cr (V)" "Cr(VI)" "Cr(III)):}`
Cr(V) is oxidized to Cr(VI) and reduced to Cr(III).
`{:((ii) , 3MnO_(4)^(-) + 4H^(+) to 2MnO_(4)^(-)+MnO^(2)+2H_(2)O),(,""Mn (VI)" "Mn(VII)" "Mn(IV)):}`
Mn (VI) is oxidized to Mn (VII) and reduced to Mn (IV).