The Enskog modulus, bρ x, has been subjected to a generalized treatment to develop reduced state correlations for nonpolar and polar substances that exhibit hydrogen bonding. These correlations present relationships between 1 + bρx and ρR, the reduced density.
For nonpolar substances, the PVT data of argon, nitrogen, methane, ethane, and carbon dioxide were used for the development of these relationships, which were found to depend on zc, the critical compressibility factor. PVT data for ammonia, methyl alcohol, and water yielded a different correlation, which is applicable to polar substances which exhibit hydrogen bonding. These relationships were found to depend on the parameter, β = (Tb-Tm)/M, which quantitatively describes the extent of hydrogen bonding for polar compounds.