During the estimation of nitrogen in an organic compound using Kjeldahl's method, the ammonia gas evolved from 1.4 g of the compound is passed into 100 mL of 0.5 M H ₂ SO ₄ . The residual acid requires 80 mL of 0.5 M NaOH for complete neutralization. The percentage of nitrogen in the organic compound is _____ .

Step-by-step solution

The total milliequivalents of H ₂ SO ₄ initially taken: meq _ initial = Volume Molarity n-factor meq _ initial = 100 0.5 2 = 100 meq The milliequivalents of NaOH used for back-titration: meq _ NaOH = 80 0.5 1 = 40 meq The milliequivalents of acid consumed by the evolved ammonia: meq _ consumed = 100 - 40 = 60 meq The percentage of nitrogen is calculated as: % N = 1.4 meq _ consumed w Substituting the values: % N = 1.4 60 1.4 = 60 Answer: 60