Generalization with the Acentric Factor

The equation of state of Starling and Han used the mixing and combining rules of eqs 5.113 to 5.124 except for the following 

Unfortunately, equations of state with this generalized form provide neither the molar volume (or the compression factor) nor other properties that are linear functions of the acentric factor as observed experimentally. 

Pitzer and co-workers and Curl and Pitzer developed a correlation for the compression factor for hydrocarbons and inorganic gases in terms of the reduced pressure and reduced temperature that is a linear function of acentric factor and is of the form 

Lee and Kesler used mixing rules for the effective critical parameters of  

The mixing and combining rules of eqs 5.151 through 5.158 provide the parameters for the mixture from those of the pure substance in terms of the 

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