Question

In a Dumas nitrogen estimation method, 0.30 g of an organic compound gave 50 cm³ of N collected at 300 K and 715 mm Hg pressure. Calculate the percentage composition of nitrogen in the compound. (‘vapour pressure of water at 300 K is 15 mm Hg)

Answer 1

P₁ = 715 – 15 = 700mm Hg, P₁ = 760 mm Hg

\(\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}\)

T₁ = 300 K, T₂ = 273 K, V₁ = 50 cm³, V₂ = ?

V₂ = \(\frac{700\times50\times273}{300\times760}\) = 41.9 cm³

% of N = \(\frac{28}{22400}\) x 41.9 x \(\frac{100}{W}\) = 17.46%