1.

0.303 g fo sample was analysed for nitrogen by Kjeldahl's method. The ammonia gas evolved was absorbed in 50 ml of 0.05 M H_(2)SO_(4). The excess acid required 25 ml of 0.1 M NaOH for neutralisation.

Answer»

`11.5`
23
`12.5`
`14.5`

Solution :No. of milli eq of `H_(2)SO_(4)` LEFT after NEUTRALISATION.
= No. of m. eq of NaOH
`= 25xx0.1xx1=2.5` m eq.
No. of m eq of `H_(2)SO_(4)` taken
`= 50xx0.05xx2=5m. eq.`
No. of eq of `H_(2)SO_(4)` ultilised for neutralisations
`= 5-2.5=2.5` m.eq.
`THEREFORE` No. of m. eq. of `NH_(3)` LIBERATED = 2.5 m.q.
% of `N=("No. of meq. of "NH_(3)xx1.4)/("wt.of org. COMPOUND")`
`= (2.5xx1.4)/(0.303)=11.55%`.


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