Question

Which of the following is a ‘False' Statement?

• A. Carius tube used in the estimation of sulphur in an organic compound (i) and (iv) are isotopes
• B. Kjeldahl’s method is used for the estimation of nitrogen in an organic compound (ii) and (iii) are isotopes
• C. Phosphoric acid produced on oxidation of phosphorus present in an organic compound is precipitated as ${\mathrm{Mg}}_2{\mathrm{P}}_2{\mathrm{O}}_7$ by adding magnesia mixture
• D. Carius method is used for the estimation of nitrogen in an organic compound

Answer 1

The correct option is D

Carius method is used for the estimation of nitrogen in an organic compound

The explanation for correct answer:

(d) Carius method is used for the estimation of Nitrogen in an organic compound

1. The Carius Halogen Method is a method for determining quantitative analysis of halogens and for estimating Sulphur ($\mathrm{S}$) in organic compounds.
2. In the Carius method, a known quantity of organic compound is heated in a hard glass tube known as a Carius tube in a furnace with fuming Nitric acid (${\mathrm{HNO}}_3$) in the presence of Silver Nitrate (${\mathrm{AgNO}}_3$).
3. The compound's Carbon and Hydrogen are oxidized to Carbon dioxide (${\mathrm{CO}}_2$) and water (${\mathrm{H}}_2\mathrm{O}$). The presence of halogen results in the formation of Silver halide ($\mathrm{AgX}$). It is filtered, rinsed, dried, and weighed, and the halogen content is calculated.
4. Similarly estimation of Sulphur ($\mathrm{S}$) in organic compound is done by heating the compound in the Carius tube, which will include Nitric acid (${\mathrm{HNO}}_3$), which will oxidise Sulphur ($\mathrm{S}$) to Sulphuric acid (${\mathrm{H}}_2{\mathrm{SO}}_4$).
5. The addition of Barium chloride solution (${\mathrm{BaCl}}_2$) to water, causes it to precipitate as Barium sulphate (${\mathrm{BaSO}}_4$). The precipitate is then washed, filtered, dried, and weighed to determine the amount of Sulphur ($\mathrm{S}$).

Therefore, Option (d) is correct. Carius Method is used for estimation of Sulphur ($\mathrm{S}$), not Nitrogen ($\mathrm{N}$).