Lead Acetate Test:

Extract + $$\text{CH}_3\text{COOH}$$ + $$(\text{CH}_3\text{COO})_2\text{Pb} \to$$

$$\text{Na}_2\text{S} + (\text{CH}_3\text{COO})_2\text{Pb}\rightarrow{\text{CH}_3\text{COOH}} \text{PbS} \downarrow \text{ (Black)} + 2\text{CH}_3\text{COONa}$$

$$\text{S}^{2-} + \text{Pb}^{2+} \to \text{PbS} \downarrow \text{ (Black)}$$

Concept:Sodium fusion extract containing sulfide ions ($$\text{S}^{2-}$$) is acidified with acetic acid ($$\text{CH}_3\text{COOH}$$) and treated with lead acetate solution. The reaction yields an insoluble black precipitate of lead sulfide ($$\text{PbS}$$).