Van der Waals Gas Calculator
Use P = nRT/(V − nb) − a(n/V)² for one gas state.
A QUICK WALKTHROUGH
How to use this tool
- Enter n in mol, V in L, T in K, a in L²·atm/mol², and b in L/mol.
- Confirm that V is greater than nb.
- Calculate pressure in atm, kPa, and bar.
Declared units and constant
All inputs use mol, L, K, L²·atm/mol², and L/mol. The fixed gas constant is R = 0.082057366 L·atm·mol⁻¹·K⁻¹; output conversions use 1 atm = 101.325 kPa = 1.01325 bar.
Fixed model scope
The calculator solves pressure for the classical Van der Waals equation only. It does not choose gas constants, find phase equilibrium, or assess model accuracy.
GOOD TO KNOW
Common questions
Why must V exceed nb?
V − nb is the free-volume denominator; the selected expression is undefined or nonphysical when it is zero or negative.
Can I enter SI constants directly?
No. Convert them to the units printed beside each input first.