Question

During estimation of nitrogen in the organic compound by Kjeldahls method, the ammonia evolved from 0.5 g of the compound in Kjeldahls estimation of nitrogen, neutralised 10 mL of 1M $H_{2}S{O}_4$. Find out the percentage of nitrogen in the compound?

• A. 14%
• B. 28%
• C. 56%
• D. 68%

Answer 1

The correct option is C 56%

In Kjeldahls method,

1M of 10ml $H_{2}S{O}_4$ $\equiv$ 1M of 20 ml $N{H}_3$

For 1000 ml of 1M $N{H}_3$ contains $14g$ of nitrogen gas

For 20 ml of 1M $N{H}_3$ contains $\frac{14}{1000}\times 20g=0.28g$ of nitrogen gas

Percentage of nitrogen will be $\frac{0.28}{0.5}\times 100$=$56$%