Question

Define the following terms with an example in each: (i) Lyophobic colloids

Answer 1

Lyophobic colloids are liquid hating colloids (Lyo means solvent and phobic means hating). In Lyophobic sol, weak forces of interaction exist between colloidal particles and liquid.
Lyophobic colloids are liquid hating colloids (Lyo means solvent and phobic means hating). When these colloids are mixed with the suitable liquid, very weak force of attraction exists between colloidal particles and liquid and system does not pass into colloidal state readily. Therefore, lyophobic sols are difficult to prepare. Special techniques are employed to prepare these sols.

Note: Water hating colloids are called hydrophobic colloids and colloidal dispersion formed is called hydrophobic sol.

Stability & Reversibility

In Lyophobic sol, weak forces of interaction exist between colloidal particles and liquid. Hence, lyophobic sols are less stable. Addition of even small quantities of electrolytes can cause particles to precipitate. Unlike Lyophilic colloids, the precipitations of lyophobic colloids do not regain their original state as coagulated mass cannot be dispersed into colloidal form. This shows that lyophobic sols are also irreversible in nature.

Electrical behavior

Under the influence of electric field the sol particles does move in definite direction. Depending upon the type of charge, they move towards anode or cathode.

Answer 2

Definition. Lyophilic : Lyophilic colloidsare liquid loving colloids (Lyo means solvent and philic means loving).Lyophobic : Lyophobic colloids are liquid hating colloids (Lyo means solvent and phobic means hating).