Enthalpy and Entropy Departure Functions for Gases
This Demonstration calculates the enthalpies and entropies for a real gas and an ideal gas as a function of temperature, relative to a reference state at a selected pressure and temperature, using the Peng–Robinson equation of state and ideal-gas heat capacities. The departure function, which is the difference between the thermodynamic property (enthalpy, entropy) for a real gas and an ideal gas at the same temperature and pressure, is also calculated. You can vary the pressure with the slider and select argon, benzene, or carbon dioxide. Select "compare all" to view departure functions for all three gases plotted as a function of temperature at 10 MPa. The departure functions in this plot are shown only above the critical tmeperature for each gas. Click "show labels" to associate each curve with a molecule.

Download the CDF file to view the simulation using the free Wolfram CDF player.