Fugacity Calculator

Summary

Calculate real gas fugacity and fugacity coefficient from temperature, pressure, and van der Waals constants.

How it works

1. Enter the temperature in Kelvin and the absolute pressure in bar.
2. Select a preset gas or enter custom van der Waals constants a and b.
3. The calculator solves the van der Waals cubic equation for molar volume.
4. Fugacity is derived from the van der Waals departure function: ln(f/P) = b/(V-b) - 2a/(RTV).
5. Results show fugacity in bar and the dimensionless fugacity coefficient phi = f/P.

Use cases

• Estimate real gas fugacity for chemical equilibrium calculations.
• Determine how much a gas deviates from ideal behavior at high pressure.
• Calculate fugacity coefficients for thermodynamic process modeling.
• Teach or verify van der Waals equation of state calculations.
• Use in phase-equilibrium and reaction equilibrium coursework.
• Compare fugacity across different gases at identical T and P conditions.

Frequently Asked Questions