Question

The fusion of an organic compound with solid sodium hydroxide is undertaken for testing nitrogen,sulphur and halogens. This test is called:

• A. Dumas method
• B. Carius method
• C. Kjeldahl's method
• D. Lassaigne's test

Answer 1

The correct option is D Lassaigne's test

It is a general test for the detection of halogens, nitrogen and sulphur in an organic compound. These elements are covalently bonded to the organic compounds. In order to detect them, these have to be converted into their ionic forms ($e.gC{N}^{-},S^{-2},P{O}_3^{-4}$ and $X^{-}$ ions). This is done by fusing the organic compound with sodium metal. The ionic compounds formed during the fusion are extracted in aqueous solution and can be detected by simple chemical tests. This is called Lassaigne's test.