On adding few drops of dil` Hcl` or `FeCl_3` to freshly precipitated ferric hydroxide , a red coloured clloidal solution is obtained . This phenomenon is known as :

Options

A. Peptization
B. Dialysis
C. Protective action
D. Dissolution

Answer

To solve the question regarding the phenomenon observed when adding dilute HCl or FeCl₃ to freshly precipitated ferric hydroxide, we will analyze the process step by step.

### Step-by-Step Solution:

1. **Understanding the Components**:
- Ferric hydroxide (Fe(OH)₃) is a precipitate that forms when iron(III) ions react with hydroxide ions.
- When dilute HCl or FeCl₃ is added to this precipitate, we observe a change in color and the formation of a colloidal solution.

2. **Identifying the Process**:
- The addition of an electrolyte (HCl or FeCl₃) to the precipitate leads to the breakdown of the precipitate into smaller particles.
- This process is known as **peptization**. Peptization involves the conversion of a precipitate into a colloidal solution by the action of an electrolyte.

3. **Chemical Reaction**:
- When HCl or FeCl₃ is added, the ferric ions (Fe³⁺) from the electrolyte interact with the hydroxide ions in the precipitate.
- The reaction can be summarized as:
\[ \text{Fe(OH)}_3 \text{ (precipitate)} + \text{Electrolyte} \rightarrow \text{Colloidal Fe(OH)}_3 \text{ (red color solution)} \]
- The presence of Fe³⁺ ions stabilizes the colloidal solution, resulting in a red color.

4. **Conclusion**:
- The phenomenon of obtaining a red-colored colloidal solution from freshly precipitated ferric hydroxide upon the addition of dilute HCl or FeCl₃ is known as **peptization**.

### Final Answer:
The phenomenon is known as **peptization**.

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