Question

During estimation of Nitrogen by Dumas' method of compound X (0.42 g) :
 
mL of $ N_2 $ gas will be liberated at STP. (nearest integer) $\text{(Given molar mass in g mol}^{-1}\text{ : C : 12, H : 1, N : 14})$

Hint:

In Dumas' method, all the nitrogen in the organic compound is converted to \( N_2 \) gas. Use the molar ratio of nitrogen in the compound to the moles of \( N_2 \) produced and then calculate the volume at STP.

Answer 1

Correct Answer: 111

M.wt of given compound = 86

Applying POAC on 'N' \( n_N \times 2 = n_{N_2} \times 2 \) 

\( n_N = n_{N_2} \) Moles of N in 0.42 g compound = \( \frac{0.42}{86} \times \frac{14 \times 1}{14} = \frac{0.42}{86} \) 

Moles of \( N_2 \) formed = \( \frac{0.42}{86} \) 

Volume \( (N_2) \) at STP = \( \frac{0.42}{86} \times 22.4 L \) 

Volume \( (N_2) \) at STP = \( 0.1108 L = 110.8 mL \approx 111 mL \)