These simulations were prepared using Mathematica. Download the free CDF player, and then download the simulation CDF file (click on the title or the figure to download below). Try to predict the behavior when a parameter changes before using a slider to change that parameter. Screencasts are provided that explain how to use these simulations.

Simulation: Phase Behavior on a Pressure-Volume Diagram

The pressure-volume phase diagram (log pressure versus log of molar volume) is shown for water. This demonstrates typical phase behavior of a single component and illustrates the concept of state functions. Drag the black dot on the P-V plot to change pressure and volume (and temperature also changes). The piston-cylinder represents the log of the volume, so that the large differences in volume between vapor and liquid can be visualized. The fluid in the cylinder is blue when liquid and green when in vapor. The intensity of the green color increases as the fluid becomes denser. 

  

Try to answer these questions before determining the solution with the simulation:

1. If a vapor-liquid mixture is heated in a fixed volume container does it eventually become all liquid or all vapor?
2. Can a liquid be converted to a vapor without a visible phase change?
   

Simulation: Injecting a Liquid into an Evacuated Tank

In this Demonstration, liquid propane or liquid toluene is injected into an evacuated 2-liter spherical tank that is held at constant temperature. When the liquid is injected, it either vaporizes completely or forms two phases in vapor-liquid equilibrium (VLE), depending on the temperature and the number of moles injected (control both with sliders). 

 

Try to answer these questions before determining the solution with the simulation:

1. Will more liquid toluene or liquid propane vaporize at the same temperature and number of moles? 
2. How does an increase in moles affect the vapor-liquid equilibrium? How about an increase in temperature?

Here is a simulation that shows the circumnavigation of the critical point on a pressure-temperature diagram.