Question

${\text{KMn}}{{\text{O}}_4}$ in basic medium is reduced to:
A. ${{\text{K}}_2}{\text{Mn}}{{\text{O}}_4}$
B. ${\text{Mn}}{{\text{O}}_2}$
C. ${\text{Mn}}{\left( {{\text{OH}}} \right)_2}$
D. ${\text{M}}{{\text{n}}^{2 + }}$

Answer 1

${\text{KMn}}{{\text{O}}_4}$ is an inorganic chemical compound. It has the ability to oxidize the acids to alcohols. It acts as an oxidizing agent in both acidic medium and basic medium. But the main difference in the reactions is the oxidation state.

Complete step by step answer:
Potassium permanganate is abbreviated as ${\text{KMn}}{{\text{O}}_4}$. It is generally a purple colored crystalline solid. It is soluble in water and other organic solvents. It is odorless and is more soluble in boiling water.
As we know that ${\text{KMn}}{{\text{O}}_4}$ is known to be a very strong oxidizing agent. It is widely used as an oxidant in different chemical experiments.
${\text{KMn}}{{\text{O}}_4}$ reacts with both and base differently. When it reacts with acids like ${\text{HCl,}}{{\text{H}}_2}{\text{S}}{{\text{O}}_4}$ etc. it gets reduced. Gaining of electrons is termed as reduction, i.e. the oxidation number or oxidation state gets reduced. Oxidizing agent is the reagent which increases the oxidation number of an element of a given substance.
Thus in alkaline medium, the reaction will be as follows:
$2{\text{KMn}}{{\text{O}}_4} + {\text{KOH}} \to 2{{\text{K}}_2}{\text{Mn}}{{\text{O}}_4} + {{\text{H}}_2}{\text{O}} + \left[ {\text{O}} \right]$
Initially, ${\text{KMn}}{{\text{O}}_4}$ forms ${{\text{K}}_2}{\text{Mn}}{{\text{O}}_4}$ in which oxidation state changes from $+ 7$ to $+ 6$. But this reaction changes as follows:
$2{{\text{K}}_2}{\text{Mn}}{{\text{O}}_4} + {{\text{H}}_2}{\text{O}} \to 2{\text{Mn}}{{\text{O}}_2} + 2{\text{KOH}} + 3\left[ {\text{O}} \right]$
Here, The oxidation state is changed from $+ 6$ to $+ 4$. Thus we can say that ${\text{KMn}}{{\text{O}}_4}$ is reduced to ${\text{Mn}}{{\text{O}}_2}$.

Hence option B is correct.

Note:
${\text{KMn}}{{\text{O}}_4}$, only in an acidic medium, acts as a strong oxidizing agent. This is because the acidic medium consumes more ${{\text{H}}^ + }$ ions, thereby forming lower ${\text{pH}}$ which favor in reduction of ${\text{KMn}}{{\text{O}}_4}$. In the basic medium, three electrons per molecule are involved. Oxidizing effect of ${\text{KMn}}{{\text{O}}_4}$ is low in an alkaline medium. This is because there is a smaller change in oxidation number in the alkaline medium than in the neutral or acidic medium.