Solve for pressure, volume, moles, or temperature in the ideal gas equation PV = nRT, with multiple unit options and mass estimates for common gases.
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Pressure
0.999998 atm
Pressure (Pa)
101324.83
Volume (L)
22.4140
n (mol)
1.0000
Temperature (K)
273.15
Mass of common gases at this n
Also in Physics
Science — Physics
The ideal gas law PV = nRT is one of the most important equations in chemistry and physics, relating the pressure, volume, amount, and temperature of a gas. This calculator solves for any one of the four variables given the other three.
PV = nRT, where P is pressure, V is volume, n is the amount of substance in moles, R is the universal gas constant (8.31446 J·mol⁻¹·K⁻¹), and T is absolute temperature in Kelvin. All values must use consistent SI units: Pa, m³, mol, and K.
The law combines Boyle's law (PV = constant at fixed T and n), Charles's law (V/T = constant at fixed P and n), and Avogadro's law (V ∝ n at fixed P and T) into a single unified equation.
At STP (0 °C, 1 atm), one mole of an ideal gas occupies 22.414 litres. At SATP (25 °C, 100 kPa, the newer standard), one mole occupies 24.790 litres.
Real gases deviate from ideal behaviour at high pressures and low temperatures. For most applications involving air, oxygen, nitrogen, and common gases at moderate conditions, the ideal law is accurate to within a few percent.
Frequently asked questions
The ideal gas law assumes gas molecules have no volume and no intermolecular attractions. At very high pressures (>10 atm) or very low temperatures (near the boiling point of the gas), real gases deviate significantly. The van der Waals equation corrects for these effects.
The ideal gas law requires absolute temperature (Kelvin) because pressure and volume are proportional to the absolute kinetic energy of the gas molecules. Using Celsius would imply negative energy at temperatures below 0 °C, which is physically meaningless.
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