A sample of 0.50 g of an organic compound was treated according to Kjeldahl's method. Ammonia evolved was absorbed in 50 mL of 0.5 M `H_2SO_4`. The residual acid required 60 mL or 0.5 M NaOH solution for neutralisation. Find the percentage composition of nitrogen in the compound.

Answer

`50 mL of 0.5 M H_2SO_4 = 50 mL 1N H_2SO_4`
`60 mL 0.5 M NaOH = 60 mL 0.5 N NaoH = 60 xx 0.5 = 30 mL 1N NaOH`
`30mL 1N NaOH solution = 30 mL 1N H_2SO_4`
Vol. of acid used up = 50-30 = 20 mL 1N `H_2SO_4`
Percentage `N_2 = (14)/1000 xx (20)/0.5 xx 100 = 5.6%`