Molar Volume Calculator Formula

Understand the math behind the molar volume calculator. Each variable explained with a worked example.

Use the Molar Volume Calculator

Formulas Used

Molar Volume

molar_volume = (0.08206 * temp) / pressure

Variables

VariableDescriptionDefault
tempTemperature (T)(K)273.15
pressurePressure (P)(atm)1

How It Works

Molar Volume of a Gas

Formula

V_m = RT / P

Where:

  • V_m = molar volume (L/mol)
  • R = 0.08206 L·atm/(mol·K)
  • T = temperature (K)
  • P = pressure (atm)

    • At STP (273.15 K, 1 atm), V_m = 22.414 L/mol for any ideal gas.

    Worked Example

    Calculate molar volume at STP (273.15 K, 1 atm).

    temp = 273.15pressure = 1
    1. 01V_m = RT / P
    2. 02V_m = (0.08206 × 273.15) / 1
    3. 03V_m = 22.414 L/mol

    Frequently Asked Questions

    What is molar volume?

    Molar volume is the volume occupied by one mole of a substance. For ideal gases, it depends only on temperature and pressure, not the identity of the gas.

    Is 22.4 L/mol always correct?

    Only at STP (0°C, 1 atm). At SATP (25°C, 1 bar), the molar volume is about 24.8 L/mol.

    Do real gases have the same molar volume?

    No. Real gases deviate due to intermolecular forces and molecular size. The deviation is quantified by the compressibility factor Z.

    Ready to run the numbers?

    Open Molar Volume Calculator