Colloidal particles in soap sol carry

Options

A. Negative charge
B. Positive charge
C. No charge
D. Either positive on negative charge

Answer

To solve the question regarding the charge of colloidal particles in soap sol, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Composition of Soap**:
Soap is typically represented by the formula RCOONa, where R is a hydrocarbon chain. When soap is dissolved in water, it dissociates into two ions: RCOO⁻ (the soap anion) and Na⁺ (sodium cation).

**Hint**: Remember that soap molecules dissociate into anions and cations when mixed with water.

2. **Understand the Behavior of Soap Ions**:
The RCOO⁻ ions (carboxylate ions) are the key players here. These ions tend to aggregate to form structures known as micelles.

**Hint**: Micelles are formed by the aggregation of soap molecules in a solution, and they play a crucial role in the properties of soap.

3. **Determine the Charge of the Micelles**:
Since the micelles are formed from the aggregation of RCOO⁻ ions, they carry a net negative charge. This is because the RCOO⁻ ions are negatively charged.

**Hint**: Focus on the charge of the ions that make up the micelles to determine the overall charge.

4. **Consider the Origin of the Charge**:
The charge on colloidal particles can arise from the preferential adsorption of ions from the surrounding medium. In the case of soap, the presence of RCOO⁻ ions leads to a negative charge on the colloidal particles.

**Hint**: The charge on colloidal particles can often be attributed to the ions that are absorbed on their surface.

5. **Conclusion**:
Based on the above points, we conclude that the colloidal particles in soap sol carry a negative charge.

**Final Answer**: The colloidal particles in soap sol carry a **negative charge**.