Question

Lyophilic sols are more stable than lyophobic sols because,

• A. the colloidal particles have positive charge.
• B. the colloidal particles have no charge.
• C. the colloidal particles are solvated.
• D. there is a strong electrostatic repulsion between the negatively charged colloidal particles.

Hint:

Remember the meanings of the terms: "lyo" refers to solvent, "philic" means loving, and "phobic" means hating. Lyophilic sols are "solvent-loving," so the strong interaction (solvation) with the solvent is their key feature and the reason for their high stability.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks for the primary reason why lyophilic sols exhibit greater stability compared to lyophobic sols.
Step 2: Detailed Explanation:
The stability of a colloidal sol depends on a few factors. Let's analyze both types of sols:
Lyophobic Sols (Solvent-Hating):
In these sols, there is little to no affinity between the dispersed phase particles and the dispersion medium. Their stability arises almost entirely from the presence of a like charge (either positive or negative) on all the colloidal particles. This charge leads to electrostatic repulsion between the particles, preventing them from aggregating and settling down.
Lyophilic Sols (Solvent-Loving):
In these sols, the dispersed phase particles have a strong affinity for the dispersion medium. Their stability is due to two main factors:
1. Charge: Like lyophobic sols, these particles also carry a charge, which causes mutual repulsion.
2. Solvation: Due to the strong affinity, the particles become extensively solvated, meaning they are surrounded by a protective layer of solvent molecules. This solvation layer acts as a physical barrier that prevents the particles from coming into direct contact and coagulating.
Conclusion:
While both types of sols can be stabilized by charge, lyophilic sols have an additional and very significant stabilizing factor: solvation. This is the key reason for their superior stability compared to lyophobic sols.
Step 3: Final Answer:
Lyophilic sols are more stable because the colloidal particles are extensively solvated, which provides an extra layer of protection against coagulation.