What volume does one mole of gas occupy at STP?

One mole of any gas at standard temperature and pressure (STP) occupies a volume of 22.4 litres.

The volume that one mole of any gas occupies at standard temperature and pressure (STP) is known as the molar volume. This is a fixed value of 22.4 litres (L) at STP. STP is defined as a temperature of 0 degrees Celsius (273.15 Kelvin) and a pressure of 1 atmosphere (atm). This concept is a fundamental aspect of the ideal gas law, which states that the volume of a gas is directly proportional to the number of moles of the gas present, given constant temperature and pressure.

The ideal gas law is usually expressed as PV=nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature. At STP, the temperature and pressure are set values, so the volume V can be calculated for any given number of moles n. For one mole of gas, the volume V is 22.4 L.

This principle applies to all gases, assuming they behave as ideal gases. Real gases can deviate from this behaviour under certain conditions, such as high pressures or low temperatures, due to intermolecular forces and the finite size of gas particles. However, under many conditions, and particularly at STP, most gases behave closely enough to ideal gases that the molar volume of 22.4 L can be used as a good approximation.

Understanding the concept of molar volume is crucial in many areas of chemistry, including stoichiometry, gas laws, and thermodynamics. It allows chemists to convert between the volume of a gas and the number of moles, which is often necessary when calculating reaction yields or designing chemical processes.