Question

Which of the following electrolyte will have maximum flocculation value for \( \mathrm{Fe(OH)}_{3} \) sol?

• A. $NaCl$
• B. $Na_{2}S$
• C. $(NH_{4})_{3}PO_{4}$
• D. $K_{2}SO_{4}$

Hint:

Low valency of coagulating ion = High flocculation value.

Answer 1

The Correct Option is A

Step 1: Concept
Flocculation value is inversely proportional to coagulating power.
Step 2: Analysis
$Fe(OH)_{3}$ is a positively charged sol. According to Hardy-Schulze rule, the ion with the lowest negative charge ($Cl^{-}$ in $NaCl$) has the lowest coagulating power.
Step 3: Conclusion
Lower coagulating power results in the maximum flocculation value.
Final Answer: (A)