Question

Flocculation value is expressed in terms of
(A) mill mole per litre
(B) mole per litre
(C) gram per litre
(D) mole per millilitre

Answer 1

Hint: Flocculation or coagulation is the phenomenon of the precipitation of a colloidal solution when we add an excessive amount of an electrolyte to the solution. Small amounts of correct electrolytes are essential for the stability of the colloids.

Complete Step-by-step Answer
Flocculation value is defined as the minimum concentration required of an electrolyte to cause the coagulation or flocculation of a solution.
Flocculation value is inversely proportional to the coagulating power of the ion.
. $ Flocculation\,\,value\,\alpha \dfrac{1}{{Coagulating\,Power}} $ .
 Different electrolytes have different coagulation capacity or flocculation value. flocculation value depends on the valency of the active ion known as flocculating ion, which is the ion that carries charge opposite to the charge present on the colloidal particles.
The Hardy Scruz rule states that greater the valency of flocculating ions, greater will be the coagulating power of that ion.
It means that the flocculation value of an electrolyte is measured from the valency or charge. higher the charge on the ion, higher will be the coagulation value.
Since Flocculation value is defined as the minimum concentration of an electrolyte. Its unit is millimole per litre.
Hence, Option (A) is correct.

Note:
Other than adding an electrolyte to the solution the following methods are also used to achieve coagulation:
Electrophoresis: In this process, the charged colloidal particles shift to the oppositely charged electrode and get discharged. This leads to the coagulation of the colloidal solution.
By mixing two opposite solutions: When two souls that have opposite charges and are mixed in a fixed proportion, then colloidal particles of one solution neutralize the charge present on the other solution. In this way, both get coagulated.