Question

In analysis of coal, determination of _______ is done by Kjeldahl method.

(a) Volatile matter

(b) Nitrogen

(c) Ash

(d) Oxygen

This question was posed to me during an internship interview.

This intriguing question originated from Analysis of Coal topic in section Fuels and Combustion of Engineering Chemistry II

Answer 1

The correct answer is (b) Nitrogen

To explain: In ultimate analysis of coal, Nitrogen is determined by Kjeldahl method. The method involves 3 steps which are digestion, distillation and titration. In digestion, sample is digested in boiling concentrated sulphuric acid in presence of catalyst and ammonium sulphate is obtained. In distillation, excess NaOH solution is added and ammonia is obtained. In titration, ammonia is determined by volumetric acid solution. The result can be expressed in terms of %N.