Van der Waals Equation Calculator
Compute pressure of a real gas from state variables and substance constants.
How to Use This Calculator
Enter moles, volume, absolute temperature, and substance constants a and b. The calculator returns real-gas pressure.
Formula
(P + a (n/V)²)(V − n b) = n R T
P = n R T/(V − n b) − a (n/V)²
About Van der Waals Equation
This real-gas equation corrects ideal gas behavior for finite molecular volume (b) and attraction (a).
Frequently Asked Questions
Where do I get a and b?
Look up substance-specific constants in tables (ensure units match SI used here).
What if V ≤ n b?
The formula becomes nonphysical. Increase V or reduce n to satisfy V > n b.