Question

Flocculation value is expressed in terms of:
A. millimole per litre
B. mol per litre
C. gram per litre
D. mol per millilitre

Answer 1

Hint: Before dealing with the question, the term flocculation needs to be introduced. Flocculation is a process in which colloids come out of suspension in the form of flake, either spontaneously or due to the addition of an emulsifying agent.

Complete step by step answer: Flocculation is the process by which fine particles are caused to clump into a floc.
-The process of flocculation:In flocculation, gentle mixing speeds up the rate of collision of particles and the destabilized particles are further aggregated into larger precipitates. Flocculation is affected by various factors including mixing speeds, mixing intensity and mixing time. The result of the mixing intensity and mixing time describes the flocculation process. The floc may then float to the top of the liquid and settle to the bottom of the liquid or be filtered from the liquid. Flocculation behaviour of soil colloids is related to freshwater quality. High dispersibility of soil colloids causes turbidity of the water and also induces eutrophication due to the adsorption of nutrition in rivers and lakes.
-Flocculation value: Minimum amount of an electrolyte required to coagulate a sol is called as its flocculation value. It is expressed in millimole per litre.
Let us see other options are units for which physical quantity:
- Gram/litre is a unit of ‘strength’. So it is an incorrect option.
- Mole/litre is a unit of ‘molarity’. So, this is also an incorrect option.
- Option ‘c’ is also incorrect as the correct option is ‘a’.
The flocculation value is expressed in millimoles per litre which is option ‘A’.

Additional Information: Coagulation and flocculation are processes in water treatment with coagulation, which helps to destabilize particles through chemical reaction between coagulant and colloids and flocculation which helps to transport the destabilized particles that will cause collisions with flake.

Note: According to Hardy-Schultz Rule, the flocculation value depends on the valency or charge of the active ion. Higher the charge higher will be the coagulating power but flocculation value will be minimum because flocculation value is inversely dependent on coagulating power.