Question

For the estimation of nitrogen, 1.4 g of an organic compound was digested by Kjeldahl method and the evolved ammonia acid absorbed in 60 mL of `M/10` sulphuric acid. The unreacted acid required 20 mL of `M/10` sodium hydroxide for complete neutralization. the percentage of nitrogen in the compound is
A. `5 %`
B. `6 %`
C. `10 %`
D. `3 %`

Answer 1

Correct Answer - C
Molarity of `H_(2)SO_(4)=M//10`
Normality of `H_(2)SO_(4)=N//5`
Molarity of `NaOH=M//10`
Normality of `NaOH=N//10`
Volume of `H_(2)SO_(4)` unreacted
`N_(1)V_(1)=N_(2)V_(2)`
`1/5xxV_(1)" "=1/10xx20`
`V_(1)" "=(20xx5)/10=10 mL`
Volume of `H_(2)SO_(4)` reacted `=60-10=50 mL`
`%` of N in the compound
`=(1.4xx"Normality of "H_(2)SO_(4)xx" Volume of "H_(2)SO_(4) " reacted")/("Mass of compound")`
`=(1.4xx0.2xx50)/1.4=10%`