Van der Waals Real Gas

Real gases aren't ideal. Compare the van der Waals isotherm to PV = nRT and see where — and why — real gases go their own way.

Van der Waals Real GasLive

where the ideal gas law breaks

Controls

Presets

Attraction a (L²·bar/mol²)

Volume b (L/mol)

Temperature (K)

Real gases deviate from PV = nRT because molecules attract each other (the a term) and occupy volume (the b term). Van der Waals adds both corrections, and below the critical temperature the isotherm even loops — predicting condensation. Educational tool.

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Data Inspector

P at V=0.3 L (vdW)86.4 bar

P at V=0.3 L (ideal)88.7 bar

Deviation-3%

Governing equation

(P + \frac{a}{V ^{2}}) (V - b) = R T, a = 1.4, b = 0.039, R T = 26.60

Reading this result: At 320 K the a and b corrections nearly cancel, so the real gas tracks the ideal-gas law to within 3%.

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How it works

The van der Waals equation corrects the ideal gas law for two real effects: molecules attract one another (the a term, lowering pressure) and occupy volume themselves (the b term, raising it). Below the critical temperature the isotherm develops a loop that signals condensation. Educational tool.

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Frequently asked questions

Is this van der waals gas calculator tool really free?▾

Yes. Van der Waals Real Gas runs entirely in your browser using your device's own compute, so local use is free forever. You only pay Compute Tokens if you scale a job to the cloud.

Do I need to install anything?▾

No. Everything runs client-side in a modern browser — no downloads, no license, no account required to start.

Can I save or share my simulation?▾

Create a free account to save projects, and use a shareable embed or minted DOI to publish a live, interactive version anywhere.

How accurate are the results?▾

The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.