Use PV=nRT to calculate moles of gas.
To use the Ideal Gas Law calculator:
The calculator solves for the number of moles using the universal gas constant R.
The Ideal Gas Law:
PV = nRT
Solved for moles: n = PV ÷ RT
Example: At STP (1 atm, 273.15 K), what volume does 1 mole occupy?
V = nRT/P = (1 × 0.08206 × 273.15) ÷ 1 = 22.414 LThis confirms the standard molar volume of an ideal gas at STP.
STP is defined as 0 °C (273.15 K) and 1 atm (101.325 kPa). At STP, one mole of any ideal gas occupies 22.414 liters. This is a standard reference point in chemistry.
The Ideal Gas Law becomes inaccurate at very high pressures (where molecules are forced close together) and very low temperatures (near a gas's condensation point). For those conditions, use the Van der Waals equation or other real gas models.