Surface tension of lyophobic sols is usually

Options

A. Lower than dispersion medium
B. More than dispersion medium
C. Equal to dispersion medium
D. Can't predict

Answer

To solve the question regarding the surface tension of lyophobic sols, we can follow these steps:

### Step-by-Step Solution:

1. **Define Lyophobic Sols**:
- Lyophobic sols are colloidal systems where the dispersed phase (the sol particles) does not have a strong affinity for the dispersing medium (usually water). This means they are "water-repelling."

2. **Understand Surface Tension**:
- Surface tension is a property of liquids that describes the elastic tendency of a fluid surface. It is the result of cohesive forces between liquid molecules.

3. **Analyze the Phases**:
- In a colloidal system, we have two phases: the dispersed phase (DP) and the dispersing medium (DM). In the case of lyophobic sols, the dispersed phase is made up of particles that repel water.

4. **Compare Surface Tension**:
- For lyophobic sols, the surface tension of the dispersed phase is usually lower than that of the dispersing medium. This is because the particles in the dispersed phase do not interact favorably with the water molecules, leading to a lower surface tension.

5. **Conclusion**:
- Therefore, the surface tension of lyophobic sols is usually lower than that of the dispersing medium.

### Final Answer:
The surface tension of lyophobic sols is usually lower than that of the dispersing medium.

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