Question

During estimation of nitrogen present in an organic compound by Kjeldahl's method, the ammonia evolved from $0.5$ g of the compound in Kjeldahl's estimation of nitrogen neutralized $10$ mL of $1M{H}_{2}S{O}_{4.}$. The percentage of nitrogen in the compound is :

• A. $56\%$
• B. $45\%$
• C. $50\%$
• D. $40\%$

Answer 1

Answer: (A)

$56\%$

10 ml of $1M{H}_{2}S{O}_4$ corresponds to 20 ml of 1M ammonia.

1000 ml of 1 M ammonia contains 14 g of nitrogen.

Hence, 20 ml of 1 M ammonia will contain $\frac{14\times 20}{1000}g$ of nitrogen.

0.5 g of organic compound contains $\frac{14\times 20}{1000}g$ of nitrogen.

Hence, 100 g of compound will contain $\frac{14\times 20\times 100}{1000\times 0.5}=56$% of nitrogen.