The Ideal Gas Law can be further extended to find the molar mass of a gas.
Concept #1: Molar Mass
Example #1: Calculate the molar mass of a gas if 2.50 g occupies 0.995 L at 715 torr and 40 ºC.
Concept #2: Ideal Gas Law Molar Mass (EASY)
Concept #3: Ideal Gas Law Molar Mass (HARD)
Example #2: An unknown gas with mass of 0.1727 g is placed into a 125-mL flask. If its pressure is 0.833 atm at 20.0ºC, what is the identity of the gas?
Practice: To identify a homonuclear diatomic gas, a chemist weighted an evacuated flask with a volume of 3.9 L then filled it with the gas at a pressure of 2.00 atm and 29.0 ºC. The chemist then re-weighted the flask and recorded the difference in mass as 8.81 g. Identify the gas.
a) H2
b) N2
c) Cl2
d) F2
e) O2
Practice: What is the molecular formula of a compound that contains 39.0% carbon, 16.0% hydrogen, and 45.0% nitrogen, if 0.1576 g of the compound occupies 125 mL with a pressure of 0.9820 atm at 295.15 K?
