Question

What are lyophilic and lyophobic colloids? Which of these sols can be easily coagulated on addition of small amounts of electrolytes?

Answer 1

Hint: Lyophilic colloids are the liquid loving colloids. Lyo means liquid and philic means loving hence, liquid loving. And lyophobic colloids are the liquid hating colloids. Lyo means liquid and phobic means hating, hence liquid hating.

Complete step by step answer:
 A colloid can be defined as a phase separated mixture in which one substance one substance of a microscopically soluble or insoluble dispersed particle is suspended throughout another substance. Every colloid consists of two parts: the colloidal particles and the dispersing medium. The colloids can be of two types. These are lyophobic colloids and lyophilic colloids.
-Lyophilic colloids: Lyophilic colloids are the colloidal solution in which the dispersed phase or the particles have a very strong affinity with the liquid. The solution of this colloid is known as lyophilic sol. These can be easily prepared by direct mixing or heating. The lyophilic sols are reversible in nature. They are quite stable and cannot be easily coagulated. The affinity of the dispersed particles with the dispersion medium is high due to the formation of a large number of hydrogen bonds.
-Lyophobic colloids: Lyophobic colloids are the colloidal solution in which the dispersed phase has very little affinity for the dispersion medium. The solution of this colloid is known as lyophobic sol and cannot be directly prepared. They are prepared by special methods. The lyophobic sols are irreversible in nature. They are unstable and can be easily coagulated by adding a small amount of suitable electrolyte.
The lyophilic sols do not easily coagulate with the addition of a small amount of electrolyte. However, adding a large amount of electrolyte may be able to do so. Whereas, the lyophobic sols can be easily coagulated with the addition of a small amount of electrolyte.

Note: The charge of the colloidal particles in lyophilic sols depends upon the pH of the medium. Whereas, in lyophobic sols, the particles have the same charge. lyophilic sols also show high colligative properties.