Question

Air is made of 80% nitrogen and 20% oxygen by volume. The densities of air and oxygen is 1.29kgm^-3 and 1.43kgm^-3 respectively. What is the density of nitrogen? Please specify your soultion,thank you!

Answer 1

Volume % = mole %

Molar mass of oxygen = 32kg/kmol

Molar mass of nitrogen = 28 kg/kmol

Density of nitrogen = Density of oxygen x molar mass of oxygen x molar ratio of air x molar mass of nitrogen

Density of nitrogen = (1.43kgm^-3)(1 kmol O2/32 kg O2)(80 kmol N2/ 20 kmol O2)(28 kg N2/1 kmol O2) = 5.01 kg/m3