Question

A green solution of potassium manganate (VI) turns purple and a brown solid is precipitated, when $C{O}_2$ gas is bubbled through the solution.

The given experiment involves:

• A. An acid – base reaction
• B. A redox reaction
• C. A disproportionation reaction
• D. A decomposition reaction

Answer 1

The correct option is C A disproportionation reaction

$K_{2}Mn{O}_4+2H_{2}O+4C{O}_2\to \underset{\left(purple\right)}{2KMn{O}_4}+\underset{\left(brownsolid\right)}{Mn{O}_2}+2KHC{O}_3$

In the above reaction the oxidation state of $Mn$ changes from +6 ($K_{2}Mn{O}_4$) to +4 ($Mn{O}_2$) and +7 ($KMn{O}_4$) so the same species is getting oxidised and reduce, hence it is a disproportionation reaction