Answer:
the average molar mass of this air sample can be calculated as
addition of the product of the average molar weights of the component gases and their percentage compositions
1. Average Molar mass of Air = 0.7803 x 28 + 0.2099 x 32 + 0.00033 x 44 = 28.58g/mol
2. The partial pressures of N2, O2, and CO2 in atm.
From Ideal gas law, at stp, Volume of air V=22.4L/mol
PV =nRT
Since, at constant temperature and pressure, the volume of a gas is directly proportional to the number of moles of the gas
Total Pressure P=1atm
Partial Pressure p = mol fraction x P
Volume of N2 = 0.7803 x 22.4L = 17.47L, Partial Pressure = 0.7803atm
Volume of O2 = 0.2099 x 22.4L = 4.68L Partial Pressure = 0.209atm
Volume of CO2 = 0.00033 x 22.4L = 0.00739L, Partial Pressure = 0.033atm
