0.50 gm of an organic compound was treated according to Kjeldahl's meghod. The ammonia evolved was absorbed in 50 ml of 0.5 `MH_2SO_4`. The residual acid required 60 ml of `(M)/(2)NaOH` solution. Find the percentage of nitrogen in the compound.

Explanation

Given that, total mass of organic compound = 0.50 g
60 mL of 0.5 M solution of NaOH was required by residual acid for neutralisation
60 mL of 0.5 M NaOH solution =`60/2` mL of 0.5 M `H_(2)SO_(4)` = 30 mL of 0.5 M `H_(2)SO_(4)`
`therefore` Acid consumed in absorption of evolved ammonia is (50–30) mL = 20 mL
Again, 20 mL of 0.5 `MH_(2)SO_(4)` = 40 mL of 0.5 `MNH_(3)`
Also, since 1000 mL of 1 MNH3 contains 14 g of nitrogen,
`therefore` 40 mL of 0.5 M `NH_(3)` will contain `(14xx40)/1000xx0.5=0.28` g of N
Therefore, percentage of nitrogen in 0.50 g of organic compound =`0.28/0.50xx100=56%`