1. The standard molar volume is the volume occupied by 1 mole of an ideal gas at standard temperature and pressure (STP), which is defined as 0°C and 1 atmosphere of pressure. The standard molar volume is 22.4 L. 2. Gases are measured in moles, with 1 mole containing 6.02 x 1023 gas particles. Equal amounts of gases in moles occupy the same volume at the same temperature and pressure conditions. 3. The ideal gas law relates the pressure (P), volume (V), amount of gas (n), temperature (T), and gas constant (R). It can be used to calculate any one variable if the others are known.