Ferric hydroxide sol is more readily conagulated by `Na_(3)PO_(4)` in comparison to KCl. Why ?

Options

A. mass of `Na_(3)PO_(4)` is more than KCl hence it is more effective than KCl
B. phosphate ion `(PO_(4)^(3-))` has higher negative charge than `Cl^(-)` ion hence are more effective for coagulation
C. KCl is more soluble than `Na_(3)PO^(4)` hence has effective for coagulation
D. `Na^(+)` ions are more effective than `K^(+)` ions for coagulation.

Explanation

To understand why ferric hydroxide sol is more readily coagulated by Na3PO4 compared to KCl, we need to analyze the charges involved in the coagulation process.

### Step-by-Step Solution:

1. **Understanding Ferric Hydroxide Sol**:
Ferric hydroxide (Fe(OH)3) forms a colloidal solution where the particles are positively charged due to the presence of Fe³⁺ ions.

2. **Coagulation Process**:
Coagulation involves neutralizing the charge of the colloidal particles. To achieve this, negatively charged ions (anions) from the coagulating agent must be introduced.

3. **Analyzing the Coagulating Agents**:
- **Na3PO4**: This compound dissociates in solution to give Na⁺ ions and PO₄³⁻ ions. The phosphate ion (PO₄³⁻) carries a charge of -3.
- **KCl**: This compound dissociates into K⁺ ions and Cl⁻ ions. The chloride ion (Cl⁻) carries a charge of -1.

4. **Comparing the Charges**:
The key difference lies in the charge of the anions:
- PO₄³⁻ has a charge of -3, which is significantly higher than the -1 charge of Cl⁻.

5. **Effectiveness of Coagulation**:
A higher negative charge (like that of PO₄³⁻) is more effective in neutralizing the positive charge of the ferric hydroxide particles. Therefore, the presence of PO₄³⁻ ions leads to a more efficient coagulation process compared to Cl⁻ ions.

6. **Conclusion**:
Since the phosphate ion (PO₄³⁻) has a higher negative charge than the chloride ion (Cl⁻), it is more effective in coagulating the positively charged ferric hydroxide sol. Thus, ferric hydroxide sol is more readily coagulated by Na3PO4 than by KCl.

### Final Answer:
Ferric hydroxide sol is more readily coagulated by Na3PO4 because the phosphate ion (PO₄³⁻) has a higher negative charge compared to the chloride ion (Cl⁻), making it more effective in neutralizing the positive charge of the ferric hydroxide particles.

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