1.216 of an organic compound was reacted under Kjeldahls method and the ammonia evolved was absorbed in 100 mL of NH,SO,. The remaining acjd solution was made upto 50 mL by the addition of water. 20 mL of the acid solution required 32 mL of caustic soda solution for complete neutralisation. Calculate the percentage composition of nitrogen in the organic compound.

Explanation

20 mL of diluted unreacted acid solution required = 32 mL of NAOH
500 mL of dilute unreacted acid solution required = `=(32)/(20) xx 50"mL of "N/10" NaOH solution"`
`="80 mL of "N/10" NaOH solution"`
`i.e, 80mL N/10 NaOH ="80mL of "N/10 H_(2)SO_(4)`
Acid used for neutralisation of `NH_(3)=(100-80)"mL of "N H_(2)SO_(4) =20"mL of "H_(2)SO_(4)`
Percentage of nitrogen `=(1.4 xx" N(acid used)" xx" V(acid used)")/("Weight of the organic compound")`
`=(1.4 xx 1 xx 20)/(1.216)=23.03%`