Question

What is a protective colloid ?

Answer 1

Lyophilic sols are more stable than lyophobic sols. This is due to the
fact that lyophilic colloids are extensively solvated, i.e., colloidal particles
are covered by a sheath of the liquid in which they are dispersed.
Lyophilic colloids have a unique property of protecting lyophobic
colloids. When a lyophilic sol is added to the lyophobic sol, the lyophilic
particles form a layer around lyophobic particles and thus protect the
latter from electrolytes. Lyophilic colloids used for this purpose are
called protective colloids.