Question

The colour of $KMnO_{4}$ disappears when oxalic acid is added to its solution in acidic medium. This can be explained as

• A. The pH of the solution changes on adding oxalic acid, hence $KMnO_{4}$is decolourised
• B. $KMnO_{4}$ Oxidizes oxalic acid to $CO_{2}$ and itself changes to $Mn^{2 +}$ions which are colourless
• C. $KMnO_{4}$ is oxidized to potassium sulphate which is colourless
• D. On exposure to air the acidic solution of $KMnO_{4}$ becomes colourless

Answer 1

Answer: (B)

$KMnO_{4}$ Oxidizes oxalic acid to $CO_{2}$ and itself changes to $Mn^{2 +}$ions which are colourless

Answer 2

:

Sol. $5C_{2}O_{4}^{2 -} + \underset{Coloured}{2MnO_{4}^{-}} + 16H^{+} \rightarrow \underset{(colourless)}{2Mn^{2 +}} + 8H_{2}O + 10CO_{2}$