A specific volume of a faintly alkaline (or strictly neutral) aqueous solution of Potassium Permanga — d and f Block Elements Chemistry Question
Question
A specific volume of a faintly alkaline (or strictly neutral) aqueous solution of Potassium Permanganate ($KMnO_4$) is allowed to react completely with an excess of Potassium Iodide ($KI$). Determine the absolute integer change in the oxidation state of the Manganese atom as it proceeds from the initial reactant to the final stable manganese product.
💡 Solution & Explanation
In a faintly alkaline or neutral medium, the permanganate ion ($MnO_4^-$), where $Mn$ is in a $+7$ oxidation state, acts as an oxidizing agent. It oxidizes $I^-$ to Iodate ($IO_3^-$) and is itself reduced to a highly insoluble, black-brown precipitate of Manganese Dioxide ($MnO_2$). In $MnO_2$, $Mn$ is in the $+4$ oxidation state. The absolute change in oxidation state is $ | (+7) - (+4) | = 3$.