Explain about the oxidation test for sulphur.

Explanation

(i) Oxidation test: The organic substances are fused with a mixture of `KNO_(3)` and `Na_(2)CO_(3)`. The sulphur if present is oxidised to sulphate.
`Na_(2)CO_(3)+S+3(O) rarr Na_(2)SO_(4) + CO_(2)`
(ii) The fused mass is extracted with water, acidified with HCl and the `BaCl_(2)` solution is added to it. A white precipitate indicates the presence of sulphur.
`BaCl_(2) + Na_(2)SO_(4) rarr underset("white ppt.")(BaSO_(4)darr) + 2NaCI`