How do you calculate molar volume of oxygen gas?
Using the Ideal Gas Law, you would find the volume of 1 mole of a gas at Standard Temperature and Pressure (STP).
STP = 1 atm of pressure and 273 K for temperature
P = 1 atm
V = ???
n = 1 mole
R = 0.0821 atm L/mol K
K = 273 K
V = 22.41 L of gas @ STP
This is also known as Avogadro's number for molar volume of a gas @ STP
I hope this was helpful.