Colloidal particles in soap sol carry

Options

A. Nagative charge
B. Positive charge
C. No charge
D. Either positive on nagative charge

Answer

**Step-by-Step Solution:**

1. **Understanding Soap and its Composition:**
- Soap is primarily made from sodium stearate, which has the chemical formula C17H35COONa. This compound is an electrolyte that dissociates in water.

2. **Dissociation of Sodium Stearate:**
- When sodium stearate dissolves in water, it dissociates into two parts: the sodium ion (Na⁺) and the stearate ion (C17H35COO⁻). The stearate ion is the key component that interacts with water.

3. **Structure of the Soap Molecule:**
- The stearate ion consists of a long hydrocarbon chain (C17H35) which is hydrophobic (water-repelling) and a carboxylate group (COO⁻) which is hydrophilic (water-attracting). The hydrocarbon chain is the tail, and the carboxylate group is the head.

4. **Behavior in Water:**
- When soap is added to water, the hydrophilic heads of the soap molecules orient themselves towards the water, while the hydrophobic tails avoid water and point away from it. This arrangement leads to the formation of structures called micelles.

5. **Formation of Micelles:**
- At low concentrations, soap molecules will arrange themselves with their heads in the water and tails sticking out. However, as the concentration increases, they form micelles, where the hydrophobic tails are shielded from water in the center, and the hydrophilic heads face outward.

6. **Charge of Colloidal Particles:**
- The micelles formed from soap contain the negatively charged stearate ions on their surface. Therefore, the colloidal particles in soap solution carry a negative charge.

**Final Answer:**
Colloidal particles in soap solution carry a negative charge.

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