Molecular Diffusion of Gases (2D)

This 2D companion to the 3D gas-effusion race models the same physics from a different angle: instead of a ballistic race to a boundary, hundreds of light and heavy gas particles perform a thermal random walk inside a shared box, starting on opposite sides of a removable partition. Once the partition lifts, the two species interdiffuse and mix, with step sizes set by a diffusion coefficient D ∝ √(T/m) — so the light species (small molar mass) always spreads faster than the heavy one, exactly as Graham's law predicts. Adjust temperature and the heavy-to-light mass ratio and watch the live diffusion-coefficient readouts and the mixing-entropy meter climb from a sharp partition line toward a uniformly blended gas.