Molecular weight of KMnO₄ is "M".in a reaction KMnO₄ is reduced to K₂MnO₄. The equivalent weight of KMnO₄ is

Expression for calculating the equivalent weight:

$\mathrm{Equivalent} \mathrm{weight}=\frac{\mathrm{Molecular} \mathrm{weight}}{\mathrm{n}-\mathrm{factor}}$

n-factor signifies the change in the oxidation state when a molecule changes into another molecule. Oxidation state of Mn in KMnO₄ is +7 and in K₂MnO₄ is +6. As there is change of only one in the oxidation state of Mn, therefore the equivalent weight of KMnO₄ is equal to its molecular weight, M.