Question

Which of the following ions will be most effective in coagulating the $A{s}_2{S}_3$ sol?

• A. $F{e}^{3+}$
• B. $B{a}^{2+}$
• C. $C{l}^{-}$
• D. ${PO}_4^{3-}$

Answer 1

The correct option is A $F{e}^{3+}$

According to the Hardy-Schulze rule - the greater the valence of the flocculating ion the greater is its ability to bring about coagulation. Iron has +3 charge, hence iron is most effective ion in the coagulation of an arsenious sulphide sol since arsenious sulphide form negative charge sol.