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In the Kjeldahl's method for estimation of nitrogen present in a soil sample, ammonia evolved from 0.75 g of sample neutralized 10 mL of 1 M $H_2SO_4$. The percentage of nitrogen in the soil is:
A
37.33
B
45.33
C
35.33
D
43.33
Detailed Solution
10 mmol $H_2SO_4$ neutralises 20 mmol $NH_3$: $H_2SO_4 + 2NH_3 \rightarrow (NH_4)_2SO_4$
$20\times10^{-3}$ mol $NH_3$ contains $14\times20\times10^{-3}$ g nitrogen.
% nitrogen $= \frac{14\times20\times10^{-3}}{0.75}\times100 = 37.33\%$
$20\times10^{-3}$ mol $NH_3$ contains $14\times20\times10^{-3}$ g nitrogen.
% nitrogen $= \frac{14\times20\times10^{-3}}{0.75}\times100 = 37.33\%$