Chemistry - Surface Chemistry Question with Solution | TestHub

According to Hardy-Schulze rule, coagulation power of ions is directly proportional to charge on ion. $\because \mathrm{Fe}(\mathrm{OH}{)}_3$ is positively charged colloid. $\therefore$ It will be coagulated by anion. (a) ${\mathrm{Mg}}_3{\left({\mathrm{PO}}_4\right)}_2\rightleftharpoons 3{\mathrm{Mg}}^{2+}+2{\mathrm{PO}}_4^{3-}$ (b) ${\mathrm{BaCl}}_2\rightleftharpoons {\mathrm{Ba}}^{2+}+2{\mathrm{Cl}}^{-}$ (c) $\mathrm{NaCl}\rightleftharpoons {\mathrm{Na}}^{+}+{\mathrm{Cl}}^{-}$ (d) $\mathrm{KCN}\rightleftharpoons {\mathrm{K}}^{+}+{\mathrm{CN}}^{-}$ Because ${\mathrm{PO}}_4^{3-}$ has highest charge among the given anions, therefore, ${\mathrm{Mg}}_3{\left({\mathrm{PO}}_4\right)}_2$ is the most effective in the coagulation of $\mathrm{Fe}(\mathrm{OH}{)}_3$ solution.