Question

Explain detection of IV group basic radicals using application of solubility product.

Answer 1

Group reagent: NH₄Cl → NH₄⁺ + Cl^– ; NH₄OH ⇌ NH₄⁺ + OH^–

H₂S ⇌ 2H⁺ + S^2- ; H⁺ + OH^– → H₂O

Radicals: Zn²⁺, Mn²⁺

Here, NH₄Cl is a strong electrolyte undergoes complete dissociation, where as NH₄OH^– and H₂S are weak electrolytes undergoes partial dissociation and attains equilibrium between their ions and molecules. Along with common ion (NH₄⁺) effect, the H⁺ and OH^- ion combines to form water molecules.

At the same time the metals forms their respective sulphides [ZnS, MnS] Whose solubility product is less than ionic product. Hence, forms precipitate.