During the estimation of nitrogen in 1.4 g of an organic compound using Kjeldahl's method, the ammonia evolved was absorbed in 40 mL of 1.0 M H ₂ SO ₄ . The excess acid required 20 mL of 1.0 M NaOH for complete neutralization. The percentage of nitrogen in the compound is ________.

Step-by-step solution

Total milliequivalents of H ₂ SO ₄ taken = Molarity n -factor Volume = 1.0 2 40 = 80 meq Milliequivalents of NaOH used in back-titration = 1.0 1 20 = 20 meq Milliequivalents of H ₂ SO ₄ neutralized by ammonia = 80 - 20 = 60 meq Milliequivalents of NH ₃ evolved = 60 meq Millimoles of nitrogen = 60 mmol = 0.06 mol Mass of nitrogen = 0.06 14 = 0.84 g Percentage of nitrogen = 0.84 1.4 100 = 60 % Answer: 60