The equivalent weight of Bayer’s reagent is (alkaline KMnO₄)

Reaction of Bayer's Reagent in alkaline medium:

$\stackrel{+7}{\mathrm{Mn}}{\mathrm{O}}_4^{-}+2{\mathrm{H}}_2\mathrm{O}+3{\mathrm{e}}^{-}\to \stackrel{+4}{\mathrm{Mn}}{\mathrm{O}}_2+{\mathrm{OH}}^{-}$

n-factor becomes 3, hence equivalent weight becomes:

$\frac{158}{3}=52.66$