Question

expalin with the help of chemical equations the principle involed in the estimation of S present in the organic compound by carius method

Answer 1

Estimation of S present in the organic compound by carius method

In this method, a known quantity of organic compound is heated with either fuming nitric acid or sodium peroxide in a hard glass tube called the Carius tube. Sulphur, present in the compound, is oxidized to form sulphuric acid. On addition of excess of barium chloride to it, the precipitation of barium sulphate takes place. This precipitate is then filtered, washed, dried, and weighed.

Let the mass of organic compound be m g.

Mass of BaSO₄ formed = m₁ g

1 mol of BaSO₄ = 233 g BaSO₄ = 32 g of Sulphur

Therefore, m₁ g of BaSO₄ contains

Principle of the sulphur estimation is to convert the sulphur compound in the form which later can be precipitated and weighed on drying i.e convert it into BaSO₄ whose sulphur content we already know in 1 mole.


Reaction involved :

Organic compound + HNO₃ -----> H₂SO₄
H₂SO₄ + BaCl2 -------> BaSO₄