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For the estimation of nitrogen, `1.4 g` of an organic compound was digested by Kjeldahl method and the evolved ammonia was absorbed in `60 mL` of `(M)/(10)` sulphuric acid. The unreacted acid required `20 mL` of `(M)/(10)` sodium hydroxide of complete neutralization. The percentage of nitrogen in the compound is:A. `6%`B. `10%`C. `3%`D. `5%` |
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Answer» Correct Answer - B Mass of organic compound `= 1.4 g` let it contain `x m` mole of `N` atom. organic compound `rarr NH_(3)` `2NH_(3)+ underset("initial taken.")underset(6 "mmole")(H_(2)SO_(4)) rarr (NH_(4))_(2)SO_(4).(1st)` `H_(2)SO_(4)underset("reacted")underset("2 mmole")(+2NaPH) rarr Na_(2)SO_(4)+2H_(2) (2nd)` Hence `m` moles of `H_(2)SO_(4)` reacted in `2nd` equation `=1` `rArr m` moles of `H_(2)SO_(4)` reatced from `1st` equation `= 6-1 = 5m` moles `rArr m` moles of `NH_(3)` in `1st` equation `= 2 xx 5 = 10 m` moles `rArr m` moles of `N` atom in the organic compound `= 10 m` moles `rArr %` of `N = (0.14)/(1.4) xx 100 = 10%` |
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