NEET2026ChemistryChapterActual
Consider the organic molecule shown in the figure. A chemist attempts to determine its nitrogen content using Kjeldahl's method. Which of the following statements correctly describes the expected result?
Options
- AThe total nitrogen content will be accurately determined as both nitrogen atoms convert to (NH₄)₂SO₄ .
- BOnly the nitrogen atom of the -NO₂ group will be converted to (NH₄)₂SO₄ , leading to an underestimation.
- COnly the ring nitrogen atom will be converted to (NH₄)₂SO₄ , leading to an underestimation.
- DThe method will fail completely because neither the ring nitrogen nor the nitro nitrogen converts to (NH₄)₂SO₄
Correct answer
D. The method will fail completely because neither the ring nitrogen nor the nitro nitrogen converts to (NH₄)₂SO₄
Step-by-step solution
Kjeldahl's method is used for the quantitative estimation of nitrogen in organic compounds. In this method, the organic compound is heated with concentrated sulfuric acid, which converts the nitrogen present in the compound to ammonium sulfate, (NH₄)₂SO₄ . However, Kjeldahl's method has specific limitations. It is not applicable to compounds containing nitrogen in: 1. Nitro groups ( -NO₂ ) 2. Azo groups ( -N=N- ) 3. Aromatic rings (e.g., pyridine, quinoline) In these types of compounds, the nitrogen atoms are not q