Unit-2: Thermodynamic Properties of Real Gases
van der Waals Equation
- The parameter b
is related to the size of each molecule. The volume that the molecules have to
move around in is not just the volume of the container V,
but is reduced to ( V
- b )
- The parameter a
is related to intermolecular attractive force between the molecules, and 1/V is
the density of molecules. The net effect of the intermolecular attractive force
is to reduce the pressure for a given volume and temperature.
-
When the density of the gas is low (i.e.,
when 1/V
is small and b is small compared to V) the van der Waals equation reduces to that of
the ideal gas law.