moles of the gas can be found using the ideal gas law, and then the molar mass can be found by
dividing the total mass of the gas by the number of moles contained.
Example: What is the molar mass of a 2.8 g sample of gas that occupies a volume of 3 L at a
temperature of 546 K and a pressure of 1.5 atm?
Solution:
molar mass = 1.24 g/L × 22.4 L/mol = 28 g/mol
The gas is therefore most likely N 2.