Question

For coagulating $A s _ { 2 } S _ { 3 }$ colloidal sol, which of the following will have the lowest coagulation value.

• A. NaCl
• B. KCl
• C. $\mathrm { BaCl } _ { 2 }$
• D. $\mathrm { AlCl } _ { 3 }$

Answer 1

Answer: (D)

$\mathrm { AlCl } _ { 3 }$

Answer 2

The amount of electrolyte required to coagulate a fixed amount of a solution depends upon the valency of the flocculation ion. The flocculating power of the various ions follows the following order, larger the valency lesser will be coagulating value. $\mathrm { Al } ^ { 3 + } > \mathrm { Mg } ^ { 2 + } > \mathrm { Na } ^ { + }$ , hence lowest coagulation value is of $\mathrm { AlCl } _ { 3 }$_..