Question

Which out of the following electrolyte solutions having the same concentration will be most effective in causing the coagulation of arsenic sulphide sol?

• A. $KCl$
• B. $MgC{l}_2$
• C. $AlC{l}_3$
• D. $N{a}_{3}P{O}_4$

Answer 1

The correct option is C $AlC{l}_3$

• The process of settling of colloidal particles is called coagulation or precipitation of the sol.
• The greater the valence of the flocculating ion added, the greater is its power to cause precipitation. This is known as a Hardy-Schulze rule.
• Arsenic sulphide is a negative sol, so we need to use a positive sol for its coagulation.
• Here, the valency of the available sols are $K^{+},M{g}^{2+},A{l}^{3+},N{a}^{+}$. So, $A{l}^{3+}$ having maximum valency and thus it will coagulate arsenic sulphide sol more.