Question

For the detection of sulphur in an organic compound, the Lassaigne's extract is acidified with dilute acetic acid and lead acetate is then added to it. The black precipitate is obtained, which is due to the formation of:

• A. $PbS$
• B. $N{a}_{2}S$
• C. $PbS{O}_4$
• D. $CaS$

Answer 1

The correct option is A $PbS$

Sulphur can also be detected by adding lead acetate to SFE, acidified with acetic acid. The formation of a black precipitate (PbS) indicates the presence of sulphur.

The detection of sulphur with lead acetate is:

$Pb(C{H}_{3}COO{)}_2+S^{2-}\to PbS\downarrow +2C{H}_{3}CO{O}^{-}$

$PbS$ is formed as a black precipitate.

Option A is correct.