Colloidal can be purified by

Options

A. Tyndall effect
B. Coagulation
C. Peptization
D. Ultrafiltration

Answer

To purify colloidal solutions, we can use several methods, including coagulation, peptization, and ultrafiltration. However, not all of these methods are effective for purification. Here’s a step-by-step explanation of the methods mentioned in the video transcript:

### Step-by-Step Solution:

1. **Understanding Colloidal Solutions**:
- Colloidal solutions consist of small particles (colloids) dispersed in a medium. These particles are typically larger than molecules but smaller than those in a suspension.

2. **Trindle Effect**:
- The Trindle effect is an optical phenomenon where light is scattered by colloidal particles, making their path visible. However, it is important to note that this is not a method of purification.

3. **Coagulation**:
- Coagulation involves the aggregation of colloidal particles to form larger particles (precipitate). This occurs when electrolytes are added, which neutralize the charges on the colloidal particles, allowing them to come together and form a precipitate.
- However, coagulation itself is not a purification method, as it leads to the formation of a precipitate rather than separating impurities.

4. **Peptization**:
- Peptization is the process of breaking down a precipitate into smaller colloidal particles by adding an electrolyte. For example, adding ferric chloride (FeCl3) to a precipitate of iron(III) hydroxide (Fe(OH)3) can lead to the formation of smaller colloidal particles.
- While this process alters the size of the particles, it does not purify the colloidal solution.

5. **Ultrafiltration**:
- Ultrafiltration is an effective method for purifying colloidal solutions. In this process, the colloidal solution is passed through a filter that allows the solvent and small particles to pass while retaining larger colloidal particles and impurities.
- This method effectively separates the colloidal particles from impurities, making it a suitable purification technique.

### Conclusion:
The most effective method for purifying colloidal solutions is **ultrafiltration**. Coagulation and peptization are processes that can alter the state of colloidal particles but do not serve as purification methods.