Gas Diffusion Container: In the Ideal Gas simulator, you model gas diffusion using a closed or open container. This vessel contains two gases that may or may not be separated by a thin membrane. The container has sensitive hotspots into which you can plug in meters that measure pressure and density of different gases inside the container. The figure to the right indicates where you hook up those meters. To place the meters, you must click directly on a hotspot (note position of cursor).

To obtain an ultrascopic view, you must click near the interface between the two gases with the Ultrascope View tool (see figure above).

In the Properties Box of the container, you can determine the type of gas particles in each half of the container: small, medium, or large. You can also color particles blue. This allows you to distinguish between two gases with particles that are the same size. You can also set the inital particle temperature.

The container can either be closed (default) or open. If you have an open container, the upper particles are small (air) by default. The density and pressure of those particles is also constant.

As diffusion proceeds during Run mode, the gray shades of the upper and bottom gases change. Darker shades of gray indicate that the gas is composed of larger, more massive particles.

The container barrier (imaginary barrier/membrane) is a separate object with its own Properties Box.

In the properties, you can choose the type of barrier: an imaginary barrier or a membrane.

If you choose membrane, you can also set the radius of the holes in the membrane. A hole of this size appears in the Ultrascope View. For smaller membrane hole sizes, larger particles cannot pass through the membrane.

The imaginary barrier can be turned on and off. This barrier has no holes, so gas cannot diffuse across it.

For the membrane to appear., the imaginary barrier must be turned on.