is: a modification of the ideal gas equation of state. [P7.5]
takes into account: the finite size of the molecules of the gas (the excluded volume effect) and the effect of long-range interactions (intermolecular forces) on the gas pressure. [P7.5]
is written: as
where 
represents the volume per mole, 
is the molar gas constant and 
and 
can be regarded as empirical constants, although they relate to intermolecular forces and to the excluded volume effect respectively. [P7.5]
Copyright 1997, The Open University