Question

Which of the following electrolytes will have maximum coagulating value for AgI/Ag⁺ solution?

Options

• Na₂S

• Na₃PO₄

• Na₂SO₄

• NaCl

Answer 1

Na₃PO₄

Explanation:

To Hardy-Schulze law, the greater the charge on anion, the greater will be its coagulating power.

Electrolytes	Anionic part	Charge on anion
\[\ce{Na2S}\]	\[\ce{S^{2-}}\]	2
\[\ce{Na3PO4}\]	\[\ce{PO^{3-}_{4}}\]	3
\[\ce{Na2SO4}\]	\[\ce{SO^{2-}_{4}}\]	2
\[\ce{NaCl}\]	\[\ce{Cl^{-}}\]	1

Here, \[\ce{PO^{3-}_{4}}\] have highest charge. Hence \[\ce{PO^{3-}_{4}}\] have height coagulating power.