Quantitative analysis of nitrogen

Question

Find the % of nitrogen in an organic compound analysed by kjeldahl method. 1.61g of the compound produced NHu200bu200bu200bu200bu200b3u200bu200bu200bu200b which was absorbed in 250 ml of N/2 Hu200bu200bu200bu200bu200bu200b2u200bu200bu200bSO4 the remaining acid was then diluted to one litre ,25 ml of which required 25.5 ml of N/10 NaOH for exact neutralisation.

Answer 1

Formula used to calculate % N by Kheldhal' method = 1.4 M 2 (V-V1/2)/Mass of organic compound.....2
V= Volume of H2SO4 taken = 250ml.
V1 = volume of NaOH = 25.5ml
M = molarity of H2SO4
normality H2SO4 = 2 x molarity H2SO4
So molarity will be half of normality of given strength
N/2 H2SO4 = M/4 H2SO4
Mass of organic compound = 1.61g
Putting the value in formula 2 we get;
% N by Kheldhal' method = 1.4 1/4 2 (250-25.5/2)/1.61= 48.80%