Question

Discuss the principle of estimation of sulphur present in an organic compound.

Answer 1

Estimation of Sulphur:

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 = `(32 xx "m"_1)/233` g of sulphur

Thus percentage of sulphure = `(32 xx "m"_1 xx 100)/(233xx"m")`