Question

The most effective coagulating agent for antimony sulphide sol is:

• A. \( \text{K}_2\text{SO}_4 \)
• B. \( \text{NH}_4\text{Cl} \)
• C. \( \text{Al}_2(\text{SO}_4)_3 \)
• D. \( \text{K}_4(\text{Fe(CN)}_6) \)

Hint:

In general, salts of aluminium and iron are the most effective coagulating agents for negatively charged sols like antimony sulphide.

Answer 1

The Correct Option is C

The coagulating agent that is most effective in coagulating an antimony sulphide sol is \( \text{Al}_2(\text{SO}_4)_3 \). This is because alum (potassium aluminium sulphate) is commonly used as a coagulating agent for sols, including antimony sulphide sols, by neutralizing the charge on the colloidal particles, which leads to their aggregation. Thus, the correct coagulating agent for antimony sulphide sol is \( \text{Al}_2(\text{SO}_4)_3 \).

Answer 2

Step 1: Understand the concept of coagulating agents
Coagulating agents help in the aggregation of colloidal particles to form larger particles, leading to precipitation. The effectiveness depends on the charge and valency of the ions involved.

Step 2: Nature of antimony sulphide sol
Antimony sulphide sol is a negatively charged colloidal solution.
To coagulate a negatively charged sol, positively charged ions with high valency are more effective.

Step 3: Role of \( \text{Al}_2(\text{SO}_4)_3 \)
Aluminium sulfate, \( \text{Al}_2(\text{SO}_4)_3 \), provides \( \text{Al}^{3+} \) ions in solution.
These trivalent aluminium ions neutralize the negative charges on antimony sulphide sol effectively, causing coagulation.

Step 4: Conclusion
Hence, \( \text{Al}_2(\text{SO}_4)_3 \) is the most effective coagulating agent for antimony sulphide sol.