An equation of state, in terms of a dimensionless Gibbs energy, has be
en developed to correlate the thermodynamic properties of benzene in t
he gas phase. This consists of an equation for the ideal gas propertie
s and a 13-term polynomial in reduced pressure and reciprocal reduced
temperature (ITS-90) which was fitted to P(rho)T, enthalpy of evaporat
ion, enthalphy differences, isobaric heat capacity and isothermal Joul
e-Thomson coefficient data. The equation has been compared with an ear
lier non-analytic equation of state developed by Goodwin (1988) and wi
th selected experimental data. The range of the equation is from 298 K
to 700 K for densities up to 0.0023 mol cm-3, but excluding a region
close to the critical point.