Example Problem: Molar Mass of a Gas from its weight and P,V,T
Problem: A sample of natural gas is collected at 25.0 oC in a 250.0 mL flask. If the sample had a mass of 0.118 g at a pressure of 550.0 Torr, what is the molecular weight of the gas? Plan:
Convert all units to K, L, atm
Use Ideal Gas Law to calculate n.
Calculate mass of vapor
Use mole / mass relationship to calculate Molar Mass