The colloidal sols are purified by

Options

A. peptization
B. coagulation
C. dialysis
D. Flocculation

Answer

**Step-by-Step Solution:**

1. **Understanding Colloidal Sols**: Colloidal sols are mixtures where tiny particles (the dispersed phase) are suspended in a medium (the dispersion medium). These particles are larger than molecules but too small to be seen with the naked eye.

2. **Need for Purification**: Over time, colloidal sols can contain impurities such as dissolved ions or small molecules (crystalloids) that need to be removed to obtain a pure colloidal solution.

3. **Method of Purification**: The most effective method for purifying colloidal sols is through **dialysis**. This process allows for the separation of colloidal particles from smaller impurities.

4. **Dialysis Process**:
- A **semi-permeable membrane** is used, which permits the passage of small particles (crystalloids) while retaining larger colloidal particles.
- The colloidal solution is placed in a container with the semi-permeable membrane separating it from pure water or another solvent.
- Due to the difference in particle size, the smaller ions and molecules diffuse through the membrane into the surrounding solvent, while the larger colloidal particles remain in the original solution.

5. **Outcome of Dialysis**: After sufficient time, the dissolved impurities are removed from the colloidal solution, resulting in a purified colloidal sol.

6. **Conclusion**: Therefore, colloidal sols are purified by the method of **dialysis**.

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