Qualitative Analysis of Lead(II) (Plumbous) Ion
If a white precipitate is obtained on adding dilute HCl to salt solution in water or while preparing original solution in dilute HCl, it indicates the presence of Pb2+ ions. White precipitates dissolves again on warming and re-precipitates on cooling.
Pb2+ + Cl– → PbCl2 (Lead chloride, white precipitate)
In case the original solution is prepared in dilute HCl, Group I is absent.
KI Test
On adding KI to hot solution of lead chloride, a yellow precipitate is obtained.
Pb2+ + 2I– → PbI2 ↓ (Lead iodide, yellow precipitate)
Potassium Chromate Test
On adding K2CrO4 solution to hot solution of lead chloride, a yellow precipitate is obtained.
Pb2+ + CrO42– → PbCrO4 ↓ (Lead Chromate, yellow precipitate)