Question

Which of the following has maximum coagulating power in the coagulation of positively charged sol?

• A. \( \text{Cl}^{-} \)
• B. \( \text{SO}_4^{2-} \)
• C. \( \text{PO}_4^{3-} \)
• D. \( [\text{Fe(CN)}_6]^{4-} \)

Hint:

Higher the charge on the coagulating ion, stronger its coagulating power according to Hardy-Schulze rule.

Answer 1

The Correct Option is D

Step 1: Understanding Coagulation Coagulation refers to the process of destabilizing a sol by neutralizing the charge on dispersed particles. According to Hardy-Schulze rule, the greater the charge on the oppositely charged ion, the greater its coagulating power. 

Step 2: Analyzing the Given Ions Since the sol is positively charged, anions with higher charge will be more effective in coagulation. The given anions have charges as follows: - \( \text{Cl}^{-} \) (Charge: -1) - \( \text{SO}_4^{2-} \) (Charge: -2) - \( \text{PO}_4^{3-} \) (Charge: -3) - \( [\text{Fe(CN)}_6]^{4-} \) (Charge: -4) 

Step 3: Applying Hardy-Schulze Rule Since \( [\text{Fe(CN)}_6]^{4-} \) has the highest negative charge (-4), it has the maximum coagulating power.