29.5 mg of organic compound containing nitrogen was digested according to Kjeldahl's method and the evolved ammonia was absorbed in 20mL of 0.1 M HCl solution. The excess of the acid required 15mL of 0.1M NaOH solution for complete neutralisation. The percentage of nitrogen in the compound is

Step-by-step solution

Weight of organic compound = 29.5 mg NH 3 + HCl → NH 4 Cl HCl + NaOH → NaCl + H 2 O (Remaining) 15 × 0.1 M = 1.5 mmol Total millimole of HCl = 2 Millimole used by N H 3 = 2 - 1.5 = 0.5 Weight of N H 3 = 0.5 × 17 mg = 8.5 mg Weight of nitrogen = 14 17 × 8.5 m g = 7 m g % N i t r o g e n = 7 29.5 × 100 = 23.7 %