Gas in a Box

Hundreds of colliding atoms. Temperature, pressure and the speed curve.

0/2challenges

0 atoms, 0 K

MeasuredMaxwell-Boltzmann

TemperatureK

Box width (piston)%

Atoms

Gas

Temperature: 0K
Most probable speed: 14m/s
Pressure, relative to full box: ...x
Measured / ideal pressure: ...

The model

Hard discs bouncing elastically off each other and the walls: no forces between them except at contact. Temperature is just their mean kinetic energy, ½ m v² = k T in two dimensions.

Collisions shuffle energy around until the speeds settle into the Maxwell-Boltzmann distribution, the curve drawn over the histogram. Pressure is measured from the momentum the discs hand the walls, and compared with the ideal gas law, P A = N k T.

Try this

Push the piston in to half the width and the pressure roughly doubles: Boyle's law. Switch to xenon at the same temperature and the discs slow down, but the pressure stays the same, because heavier atoms hit harder.

Two-dimensional hard discs. The measured pressure runs a little above ideal because the discs take up room, which is what the van der Waals correction is for. Educational model, not an engineering design or validation tool.

Achievements0/2

Hot gas +20Heat the gas past 1,000 K.
Boyle +30Halve the volume and watch the pressure double.

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