Sulphur Detection
In Lassaigne's test, sulphur is detected by formation of:
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About This Question
- Subject
- chemistry
- Chapter
- purification techniques
- Topic
- sulphur detection
- Difficulty
- Easy
- Year
- 2025
Solution
Correct Answer:
Black PbS precipitate
- Sodium Fusion: Na+S→Na2S (Sodium sulphide).
- Preparation: The fusion extract is acidified with acetic acid.
- The Test: Lead acetate solution ((CH3COO)2Pb) is added to the extract.
- Observation: A distinct black precipitate of Lead Sulphide (PbS) is formed.
- Equation: S2−+Pb2+→PbS↓.
- Alternative: Sulphur can also be detected by the Sodium Nitroprusside test, which gives a deep violet coloration (forming Na4[Fe(CN)5NOS]).
This easy difficulty chemistry question is from the chapter purification techniques, covering the topic of sulphur detection. It appeared in the 2025 exam.
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