Qualitative Analysis - Test for Sulphur

Description:

The Lassaigne’s extract contains sodium sulphide.

2Na + S → Na₂S

Confirmatory tests

• Lead Acetate Test
• Sodium Nitroprusside Test

Lead Acetate Test

Sodium fusion extract is acidified with acetic acid and lead acetate is added to it. A black precipitate of lead sulphide indicates the presence of Sulphur.

S²⁻ + Pb(CH₃COO)₂ → PbS ↓ (black ppt) + 2CH₃COO⁻

Sodium Nitroprusside Test

The appearance of a deep violet color upon addition of a few drops of sodium nitroprusside to fusion extract indicates the presence of sulfur.