Among the following electrolytes, which is the most effective coagulation agent for `Sb_(2)S_(3)` solution?
(a)`Na_(2)SO_(4)`
(b)`CaCl_(2)`
(c)`Al_(2)(SO_(4))_(3)`
(d)`NH_(4)Cl`

Options

A. `Na_(2)SO_(4)`
B. `CaCl_(2)`
C. `Al_(2)(SO_(4))_(3)`
D. `NH_(4)Cl`

Answer

C

Explanation

`Sb_(2)S_(3)` solution is a negatively charged solution. The process by means opf which the particles of the dispersed phase in a solution are precipitated is know 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 coagulation or flocculating power of the active ion increases with the valency of the active ion. Greater the valency of the active ion, greateer ios its power to cause coagulation. This is known as Hardy Schulze rule. For a negatively charged solution,
`Al^(3+)gtCa^(2+)gtNa^(o+)=NH_(4)^(o+)`