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For Educators · Entropy

Entropy for a glass pane

Built for educators teaching it to a class. Drop a live demo into a lecture or assign it as a shareable link — no lab installs. Simulate a glass pane live below — adjust the inputs and watch it respond, right in your browser.

Entropy & Free ExpansionLive

the second law in action

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Gas confined to one half rushes to fill the whole box the instant the partition is removed — and never spontaneously crowds back. That irreversibility is the second law: entropy, a measure of disorder, always increases. For doubling the volume the entropy rises by nR·ln2, purely because there are vastly more ways to be spread out than packed in.

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Data Inspector

Fraction on left100%

ΔS (per mole)0.00 J/K

Stateconfined

Governing equation

Δ S = n R ln \frac{V _{f}}{V _{i}} = R ln 2 = 0.00 J/K

Reading this result: All 120 particles are trapped in the left half — entropy is at its lowest. Remove the partition to watch it climb.

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Frequently asked questions

Is this good for educators?: Yes — this version of "Entropy for a glass pane" is framed for educators teaching it to a class. Drop a live demo into a lecture or assign it as a shareable link — no lab installs.
Do I need to install anything?: No. It runs in any modern browser, free, with no account required.