Question

In Lassaigne's test, the organic compound is fused with sodium metal as to:

• A. Hydrolyse the compound
• B. Form a sodium derivative
• C. Convert nitrogen, sulphur or halogens if present into soluble ionic sodium compound
• D. Burn the compound

Answer 1

The correct option is C Convert nitrogen, sulphur or halogens if present into soluble ionic sodium compound

Lassaigne's test is used for the detection of elements: Nitrogen (N), Sulfur (S), Chlorine (Cl), Bromine (Br) and Iodine (I). This test involves below mentioned two steps.
(i) Preparation of sodium fusion extract (SFE). The ionic compounds formed during the fusion are extracted in aqueous solution and can be detected by simple chemical tests.
(ii) Detection of elements using SFE.
The elements in the organic compound react with sodium during fusion reaction as follows:
$Na+C+N\to NaCN\text{(if N is present)}$
$2Na+S\to N{a}_{2}S\text{(if S is present)}$
$Na+S+C+N\to NaSCN\text{(if both N and S are present)}$