Question

Among the following electrolytes, which is the most effective coagulating agent for $S{b}_2{S}_3$ solution?

• A. $N{a}_{2}S{O}_4$
• B. $CaC{l}_2$
• C. $A{l}_2(S{O}_4{)}_3$
• D. $N{H}_{4}Cl$

Answer 1

The correct option is C

$A{l}_2(S{O}_4{)}_3$

$S{b}_2{S}_3$ solution is a negatively charged solution. The process by means of which the particles of the dispersed phase in a solution are precipitated is known as coagulation or flocculation. An ion having an opposite charge to that of the solution is responsible for coagulation. This ion is thus known as active ion. The coagulating or flocculating power of the active ion increases with the valency of the active ion. Greater the valency of the active ion, greater is its power to cause coagulation. This is known as Hardy Schulze rule. For a negatively charged solution, $A{l}^{3+}>C{a}^{2+}>N{a}^{\oplus }=N{H}_4^{\oplus }.$