In Dumas method for estimation of nitrogen, 0.50 g of an organic compound gave 70 mL of nitrogen collected at 300 K and 715 mm pressure. The percentage of nitrogen in the organic compound is _ _ _ _ %. (Aqueous tension at 300 K is 15 mm).

Step-by-step solution

Given data: Mass of organic compound ( w ) = 0.50 g Volume of nitrogen gas ( V₁ ) = 70 mL Temperature ( T₁ ) = 300 K Total pressure = 715 mm Hg Aqueous tension = 15 mm Hg Pressure of dry nitrogen ( P₁ ) = 715 - 15 = 700 mm Hg Convert the volume of nitrogen to STP conditions ( P₀ = 760 mm Hg, T₀ = 273 K): Using the combined gas law: P₁ V₁ T₁ = P₀ V₀ T₀ V₀ = P₁ V₁ T₀ P₀ T₁ = 700 70 273 760 300 58.68 mL At STP, 22400 mL of N₂ weighs 28 g. Mass of N₂ collected = 28 58.68 22400 g Percentage of nitrogen = Mass of N₂ Mass