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What is the purpose of the Lassaigne’s test in organic chemistry?
What is the purpose of the Lassaigne’s test in organic chemistry?
The purpose of the Lassaigne’s test is to detect the presence of nitrogen, sulfur, and halogens in organic compounds by converting them into ionic form for easier identification.
How is the presence of nitrogen detected in the Lassaigne’s test?
How is the presence of nitrogen detected in the Lassaigne’s test?
Nitrogen is tested with concentrated H2SO4, and the appearance of a prussian blue color indicates its presence.
What indicates the presence of sulfur in the sodium fusion extract?
What indicates the presence of sulfur in the sodium fusion extract?
The presence of sulfur in the sodium fusion extract is indicated by a violet color when reacting the extract with sodium nitroprusside.
How are halogens tested in the Lassaigne’s test?
How are halogens tested in the Lassaigne’s test?
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What is the process for extracting ionic sodium sulfide in the Lassaigne’s test?
What is the process for extracting ionic sodium sulfide in the Lassaigne’s test?
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Study Notes
Lassaigne’s Test Purpose
- Used to detect the presence of certain elements in organic compounds, specifically nitrogen, sulfur, and halogens.
- Involves fusing an organic sample with sodium to extract the ionic species into an aqueous solution.
Detection of Nitrogen
- Presence of nitrogen is detected by forming sodium cyanide from the fusion of sodium with nitrogen-containing compounds.
- A subsequent reaction with ferrous sulfate yields Prussian blue color if nitrogen is present, indicating the formation of ferric ferrocyanide.
Indication of Sulfur
- Sulfur presence is indicated by the formation of a yellow precipitate of barium sulfate when the sodium fusion extract is treated with barium chloride.
- Alternatively, the presence of sodium sulfide can also be tested, typically resulting in a black precipitate with lead(II) acetate if sulfur is present.
Testing for Halogens
- Halogens are tested by adding silver nitrate to the sodium fusion extract.
- Formation of a white precipitate indicates chloride, a pale yellow precipitate indicates bromide, and a yellow precipitate indicates iodide presence.
Extraction of Ionic Sodium Sulfide
- Sodium sulfide is extracted from the organic sample during the fusion process.
- The fusion of sodium with the organic compound in a fusion tube allows sulfur-containing compounds to interact with sodium, resulting in the formation of sodium sulfide in the aqueous extract.
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Description
Test your knowledge of organic chemistry lab experiments with this quiz on Sodium Fusion. Explore the procedure, results, and observations of the experiment and enhance your understanding of detecting nitrogen, sulfur, and halogens in organic compounds.
