Question

Lassaigne extract having $N{a}_{2}S$ when acidified with acetic acid and on addition of lead acetate produces a black precipitate of :

• A. $C{H}_{3}COONa$
• B. $PbS$
• C. $Pb(C{H}_{3}COO{)}_2$
• D. $PbO$

Answer 1

The correct option is B $PbS$

Lead acetate test: Lassaigne extract is acidified with acetic acid and then lead acetate solution is added. Formation of a black precipitate confirms the presence of sulphur in the organic compound.
$N{a}_{2}S+Pb(C{H}_{3}COO{)}_2\to \underset{\text{Black}}{PbS}\downarrow +2C{H}_{3}COONa$