Question

Give a Reason for the Following:

For Ferric Hydroxide Sol. the Coagulating Power of Phosphate Ion is More than Chloride Ion.

Answer 1

This is because  `"P" O"_4^(3-)` ion has more charge than Cl^– ion.

Answer 2

Ferric hydroxide is a positively charged sol, therefore it will coagulate upon the addition of an anion. According to the Hardy-Schulze rule, the greater the valence of the flocculating ion (charge on ion) added, the greater is its power to cause precipitation or coagulation. Therefore, phosphate ion \[\ce{PO^{3-}_4}\] being trivalent will coagulate the sol more readily than monovalent chloride ion Cl⁻.

Negative charge on \[\ce{PO^{3-}_4 > Cl^-}\]

∴ Coagulating power of \[\ce{PO^{3-}_4 > Cl^-}\]