Colloids are the particles having size between 1nm to 1000nm such as H20, Alcohol, Benzene are assumed to be aggregate of many small molecules which have high molecular mass. They have the ability to scatter light and have low osmotic pressure.
Colloidal systems are divided into two parts–
i. Lyophilic Colloids
ii. Lyophobic Colloids
The Lyophobic Colloids are polymeric molecules and Lyophilic Colloids are proteins or starch in water, rubber in benzene.
They are solvent hating colloids. When the dispersed phase has less affinity for dispersion medium, the system is called Lyophobic Colloids.
When dispersion medium is water, they are given the name Hydrophobic. If they are separated, they can not be made by simply adding with dispersion medium.
ii. Lyophilic Colloids:
When the dispersed phase has the highest affinity for dispersion medium, then it is called Lyophilic Colloids.
When the dispersed phase is separated from dispersion medium, they can be again made by simply remixing with the dispersion medium.