Answer to Question #129180 in General Chemistry for Hadassah

Question

When organic compound and sodium metal is tested. Lassaigne's extract was observed. What is the inference?

Answer 1

 When the organic compound is heated with sodium, the elements such as nitrogen, sulphur and halogens, if present in the compound, are converted into sodium salts which are soluble in water. The aqueous solution is then used to identify these elements.

The sodium fusion test, or Lassaigne's test, is used in elemental analysis for the qualitative determination of the presence of foreign elements, namely halogens, nitrogen, and sulphur, in an organic compound. It was developed by J. L. Lassaigne.

The test involves heating the sample strongly with clean sodium metal, "fusing" it with the sample. A variety of techniques has been described. The "fused" sample is plunged into water, and the usual qualitative tests are performed on the resultant solution for the respective possible constituents