Which from following anions has lowest coagulating power for precipitation of positive sol?
Which from following anions has lowest coagulating power for precipitation of positive sol?
$\left[\mathrm{Fe}(\mathrm{CN})_6\right]^4$.
$\mathrm{PO}_4^{3-}$
$\mathrm{SO}_4^{2-}$
$\mathrm{Cl}^{-}$
Solution
According to Schulze-Hardy rules, the ions having opposite charge to sol particles cause coagulation and greater the valency of oppositely charged ion, more is the coagulating power. Hence, the decreasing order of coagulating power for precipitation of positive sol is $\mathrm{Fe}(\mathrm{CN})_6^4\gt\mathrm{PO}_4^{3-}\gt\mathrm{SO}_4^{2-}\gt\mathrm{Cl}^{-}$