Van de Waals Equation of State
The y axis shows the pressure P in pascal, and the x-axis shows the volume Vm of one mole of a substance in cubic metres. Three curves are shown.

Graph of the formula

The parameters of the curve shown do not correspond closely with any real gas, but are similar to those for argon. The curves above correspond to a temperature of around 50 K. Notice that:


The animation below shows the effect of varying the temperature of the substance from around 15 K up to 100 K. This spans the region in which this argon-like substance would be expected to condense. Notice that:


The Graphing Calculator Equations for the above equations are shown below

R=8.31,b=24*10^(-6),a=2/3*R*b*80

y=R*T/x

y=R*T/[x-b]

y=[if(R*T/[x-b]-a/x^2,x>b)]

x=b


This file was created by Graphing Calculator 3.0.
Visit Pacific Tech to download the helper application to view and edit these equations live.