A sample of 0.50g of an organic compound was treated according to Kjeldahl's method. The ammonia evolved was absorbed in 50ml of `0.5M H_(2)SO_(4)`. The residual acid required 60mL of 0.5M solution of NaOH for neutralisation. Find the percentage composition of nitrogen in the compound

Explanation

Initially taken `H_(2)SO_(4)= 50mL 0.5M`
used NaOH = 60 mL 0.5M
`:.` unused `H_(2)SO_(4)= 30 mL 0.5M H_(2)SO_(4)`
used `H_(2)SO_(4)= (50-30)= 20 mL 0.5 H_(2)SO_(4)`
`=40 mL 0.5M NH_(3)`
`1000 mL 1M NH_(3)= 17g NH_(3)=14g` nitrogen 40mL 0.5M `NH_(3)=`
`=(40 mL xx 0.5M xx 14g)/(1000mL xx 1M)= 0.280` g nitrogen
% N `= (0.280 xx 100)/(0.5)= 56`
`:.` % of nitrogen = 56%