Write short note on
Coagulation or flocculation

Explanation

Coagulation: The process of aggregation of colloidal particles into an insoluble precipitate by the addition of some suitable electrolyte is called coagulation.
The ion of the electrolyte which neutralises the charge on the colloidal particles is called effective ion.
(a) For negatively charged sols like `As_2 S_3` sol, the effective ion is cation of the electrolyte.
(b) For positively charged sols like Fe `(OH)_3` sol, the effective ion is anion of the electrolyte.