For the estimation of nitrogen, 1.4 g of an organic compound was digested by Kjeldahl method and the evoled ammonia was absorbed in 60 mL of M/10 sulphuric acid. The unreacted aicd required 20 mL of M/10 sodium hydroxide for complete neutralisation. The precentage of nitrogen in the compound is-

Options

A. 0.05
B. 0.06
C. 0.1
D. 0.03

Answer

C

Explanation

Absorbed acid = 60 mL `((M)/(10))H_(2)SO_(4)=60mL((1)/(10)xx2)NH_(2)SO_(4)=12mL(N)H_(2)SO_(4)` solution
Sodium hydroxide required for the neutralisation of excess amount of acid 20 mL `((M)/(10))NaOH=20mL1//10`
`(N)NaOH=2mL(N)NaOH` solution
Now, 2mL (N) NaOH = 2 mL (N) `H_(2)SO_(4)`
`therefore " " "Amount of acid required for the neutralisation of liberated " NH_(3)=12mL(N)H_(2)SO_(4)-2mL(N)H_(2)SO_(4)`
`=10mL(N)H_(2)SO_(4)=10mL(N)NH_(3)`
1000mL (N)`NH_(3)` solution contains 17g `NH_(3)-=14 gN`
`therefore "10ml(N)NH_(3)" " solution contains"`
`=(17xx10)/(1000)gNH_(3)-=(14xx10)/(1000)gN.`
`"Hence, 1.4 of the compound contains"=(14xx10xx100)/(1000xx1.4)=10gN.`
`therefore "The compound contains 10%nitrogen"`.