The van der Waals equation of state for water is used to generate isotherms on a pressure-log volume (P-V) diagram and isobars on a temperature-log volume (T-V) diagram. Sliders change the isotherm temperature on the P-V diagram and the isobar pressure on the T-V diagram. Liquid and vapor are in equilibrium within the phase envelope, which was generated from data for water. The isotherms and isobars have three solutions in the two-phase region, but the only physically-meaningful conditions are the orange dots, which correspond to saturated liquid and saturated vapor. The saturated liquid volume (V_L) and the saturated vapor volume (V_V) are displayed. The horizontal, dashed orange line (at P_sat and T_sat) represents a mixture of liquid and gas. On the P-V diagram, the green area above the orange line is equal to the area below the orange line when plotted on a linear volume scale.

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About:

This simulation was made at the University of Colorado Boulder, Department of Chemical and Biological Engineering.  Author(s): Rachael L. Baumann

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