Question

What happens when a lyophilic sol is added to a lyophobic sol ?
a.) Lyophilic sol is protected
b.) Lyophobic sol is protected
c.) Both the sols are coagulated
d.) Electrophoresis takes place

Answer 1

Hint: Lyophilic sols are more stable than lyophobic sols because lyophilic the lyophilic colloids are highly solvated. Lyophilic sols are guards of lyophobic sols.

Complete answer:
We have studied that lyophilic sols are very stable in nature. This is due to strong interaction forces between the dispersed phase and dispersion medium. In these, the colloidal particles are covered by a sheath of liquid in which they are dispersed.
When a lyophilic sol is added to the lyophobic sol, the lyophilic particles form a layer around lyophobic particles which are not so stable. Due to greater stability of lyophilic sols, lyophobic sols protect them from electrolytes.
So, the correct answer is “Option B”.

Additional Information:
Colloids are liquid in nature. These substances either do not pass or pass very slowly through the membrane. Basically, two types of colloids are present.
Lyophilic colloids – When the particles of the dispersed phase and dispersion medium have strong attractions towards each other then the sol formed is Lyophilic sol.
Example- Starch, proteins and gelatin etc.
Lyophobic colloids – When the particles of the dispersed phase and dispersion medium do not have attractions towards each other then the sol formed is Lyophobic sol.
Example- Gold, silver and metal hydroxides etc.
The lyophobic sols are stabilised due to charge only. Thus, they are less stable.

Note: The Lyophilic colloids are also named as protective colloids because of their protecting behaviour towards lyophobic colloids. These act as a shield to lyophobic colloids.
The lyophobic colloids have no attractions between particles of the dispersion medium and dispersed phase. So, they coagulate very easily while this does not happen in the case of lyophobic sols.