Fugacity of a Single Component: Simulations
These simulations were prepared using MathematicaDownload the free CDF player, and then download the simulation CDF file (click on the title or figure of the simulation below). Try to predict the behavior when a parameter changes before using a slider to change that parameter. For these simulations, screencasts are provided to explain how to use them.

Two 1-liter flasks are at different temperatures; the left flask contains water with dissolved salt and the right flask contains pure water. You can control the temperature of the left flask and the amount of salt dissolved with the sliders. Select the reset button and then select play ("go to equilibrium"). Water transfers from one flask to the other to try to make water fugacities equal in each flask. For some conditions, all the water transfers to the left or right flask. Check "show fugacities" to display the water fugacities in each flask.

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

1. How does changing the temperature affect equilibrium?
2. How does changing the amount of salt affect equilibrium?

Simulation: Fugacity from Equation of State for Water

The Peng-Robinson equation of state (EOS) is used to calculate the fugacity, f, and the fugacity coefficient, Φ, for pressures and volumes which can be selected by sliders. The fugacity coefficient indicates how much the fluid deviates from ideal-gas behavior; it equals 1 for an ideal gas. Isotherms are shown on the P-V diagram when you select "isotherms" from the drop-down menu. The constant temperature region inside the phase envelope is represented by a solid horizontal line.

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

1. Does the fugacity change with an increase of volume or pressure? Does it matter if there are two phases present or if it is supercritical?
2. How do isotherms change with temperature?