Question

In the Kjedahl's method for estimation of nitrogen present in soil sample, ammonia evolved from $0.75$g of sample neutralized 10ml. of $1M{H}_{2}S{O}_4$. The percentage of nitrogen in the soil is:

• A. $37.33$
• B. $445.33$
• C. $35.33$
• D. $43.33$

Answer 1

The correct option is A $37.33$

10 ml of $1M{H}_{2}S{O}_4$ corresponds to 10 mmol.

It will neutralize 20 mmol of $N{H}_3$.

Weight of $N=\frac{14\times 20}{1000}g=0.280g$.

Thus 0.75 g of sample of organic compound contains 0.280 g of nitrogen.

The percentage of nitrogen in the organic sample is $\frac{0.280}{0.75}\times 100=37.33$%.