Consider the reaction, ${\mathrm{Cl}}_2\stackrel{{\mathrm{OH}}^{-}}{\to }{\mathrm{Cl}}^{-}+{\mathrm{ClO}}^{-};$Equivalent weight of chlorine in this equation is('M' is the molecular weight of chlorine)

$\stackrel{0}{\mathrm{C}}{\mathrm{l}}_2\stackrel{{\mathrm{OH}}^{-}}{\to }{\mathrm{Cl}}^{-}+\stackrel{+1}{\mathrm{C}}{\mathrm{lO}}^{-};$

It is a disproportionation reaction;

Chlorine is both oxidant and reductant;

Increase in o.s/ mole of chlorine= $\frac{1}{{\displaystyle \frac{1}{2}}}$=2

Decrease in o.s/ mole of chlorine= $\frac{1}{{\displaystyle \frac{1}{2}}}$=2

Equivalent weight of chlorine= $\frac{\mathrm{M}}{2}+\frac{\mathrm{M}}{2}=\mathrm{M}$