Molar volume is the volume occupied by one mole of a substance (usually a gas) at a given temperature and pressure.
Key points:
- It is generally used for gases because their volume depends on temperature and pressure.
- At Standard Temperature and Pressure (STP: 0 °C and 1 atm), the molar volume of an ideal gas is 22.4 liters per mole.
- If STP is defined as 0 °C and 1 bar (according to IUPAC), the molar volume is about 22.7 liters per mole.
- The molar volume links the amount of gas (in moles) to the space it occupies, making it easier to calculate volumes of gases in chemical reactions.
In short: Molar volume is the space one mole of a gas takes up under standard conditions.