1.4 g of an organic compound was digested according to Kjeldahl's method and the ammonia evolved was absorbed in 60 mL of M/10 H 2 S O 4 solution. The excess sulphuric acid required 20 mL of M/10 NaOH solution for neutralization. The percentage of nitrogen in the compound is:

Step-by-step solution

Total millimoles of sulphuric acid = 60 × 1 10 = 6   m m   H 2 S O 4 Excess H 2 S O 4 ≡ 20 × 1 10 × 1 2 = 1   m m   H 2 S O 4 H 2 S O 4 used in reaction with ammonia = 6 - 1 = 5   m m Based on the reaction stoichiometry, 2 N H 3 + H 2 S O 4 ⟶ N H 4 2 S O 4 mm of N H 3 = 10   m m Mass of N = 10 × 10 - 3 × 14 g m o l e = 0.140 g %   N 2 = 0.140 1.4 × 100 = 10 %