Chemistry · Quantitative analysis (basic principles only): Estimation of carbon, hydrogen, nitrogen, halogens, sulphur and phosphorus

of an organic compound containing nitrogen on kjeldahlising required of for comp

\( 0.5 g \) of an organic compound containing nitrogen on kjeldahlising required \( 29 m l \) of \( N / 5 H_{2} S O_{4} \) for complete neutralisation of ammonia. The percentage of nitrogen in the compound is :

  • A. 34.3
  • B. 16.2
  • C. 13.6
  • D. 24.5

Step-by-step solution

In Kjeldahl method, nitrogen is converted to ammonia. The volume of N/5 H2SO4 used is 29 mL, which is 0.029 L of 0.2 N acid. Equivalents of H2SO4 = 0.2 × 0.029 = 0.0058. This equals equivalents of NH3, which equals moles of N (since each N gives one NH3). Mass of N = 0.0058 × 14 = 0.0812 g. Percentage = (0.0812/0.5) × 100 = 16.24%, approximately 16.2%.
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