Final answer:
At STP (0°C and 1 atm), one mole of any gas occupies a volume of 22.4 liters, which is referred to as the standard molar volume.
Step-by-step explanation:
At standard temperature and pressure (STP), which is 0 degrees Celsius (273 K) and 1 atmosphere pressure, one mole of any gas occupies a volume of 22.4 liters. This concept is known as the standard molar volume and is based on the ideal gas law.
This volume makes for a very convenient conversion factor in stoichiometry problems, as long as the conditions are indeed at STP. If conditions differ from STP, adjustments must be made using the ideal gas law or the combined gas law to determine the actual volume occupied by a gas.