A sample of 0.50 g of an organic compound was treated according to Kjeldahl's method. The ammonia evolved was absorbed in 50 mL of 0.5 M H ₂ SO ₄ . The residual acid required 60 mL of 0.5 M solution of NaOH for neutralisation. The percentage of nitrogen in the compound is

Step-by-step solution

Volume of acid taken =50 ~mL of 0.5 MH ₂ SO ₄ =25 ~mL of 1 M H ₂ SO ₄ Volume of alkali used for neutralisation of excess acid. =60 ~mL of 0.5 M NaOH =30 ~mL of 1 M NaOH Now 1 mole of H ₂ SO ₄ neutralises 2 moles of NaOH, (i.e, H ₂ SO ₄+2 NaOH Na ₂ SO ₄+ H ₂ O ) 30 ~mL of 1 M NaOH =15 ~mL of 1 M H ₂ SO ₄ Volume of acid used by NH ₃=25-15=10 ~mL Now % ~N = 1.4 M B V Mass of the substance taken = 1.4 1 2 10 0.5 =56 ~g