In: Chemistry
Assume for the moment that air consists of 80.00% nitrogen (N2) and 20.00% oxygen (O2) by volume. Use these figures and typical values for temperature and pressure (1.000atm and 25.00°C) to calculate the density of air in g/L.
Answer – We are given, percent of N2 in air = 80.00 %
For O2 = 20.00 % , P = 1.00 atm , T = 25 +273 = 298 K
We need to calculate the mass of N2 and O2
mass of N2 = 28.014*80.0 % / 100 %
= 22.41 g
Mass of O2 = 31.998 g * 20.0 % / 100 %
= 6.399 g
So total mass of air = 22.41 +6.399
= 28.81 g
We know formula for calculating the density
Density = PM/RT
= 1.00 atm * 28.81 g / 0.0821 atm.L.mol-1.K-1 * 298 K
= 1.18 g/L
The density of air is 1.18 g/L