  We consider thermodynamics of the excluded volume particles at finite
temperature and chemical potential, in the low density approximation. We assume
Boltzmann statistics and study the influence of the excluded volume on an ideal
gas thermodynamics at the same temperature, pressure and numbers of particles.
We show, that considering the change of the free enthalpy due to the excluded
volume, and using the Maxwell identities, one can derive relevant thermodynamic
functions and parameters of multi-component gases. The derivation is quite
general as particles may have different sizes and shapes which can also depend
on their momenta. Besides it's simplicity and generality, our approach has the
advantage of eliminating the transcendental equations occurring in earlier
studies. A representative example of the excluded volume thermodynamics is the
single-component gas of hard spheres. For this case, using the viral expansion,
the validity limits of the low-density approximation are also discussed.
