Question

For the coagulation of positively charged hydrated ferric-oxide sol, the flocculating power of the ions is in the order:

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

Hint:

Flocculating power increases with ion charge per the Schulze-Hardy rule.

Answer 1

The Correct Option is D

The flocculating power of ions depends on their charge according to the Schulze-Hardy rule. Higher charged ions have greater flocculating power.