Eqns. 8.22–8.30 stand out in this chapter as the starting point for deriving the necessary departure function expressions for any equation of state. It is tempting to use spreadsheets or programs to add up the contributions from departure functions, reference states, and ideal gas temperature effects mindlessly, like a human computer. But keep in mind that a major goal is to teach the development of model equations, as well as their application. Your skill in developing model equations for novel applications can transcend the study of thermodynamics. Master the derivations behind the programs as well as the mechanics of implementing them.
Figure 8.7. Generalized charts for estimating (H – Hig)/RTc using the Lee-Kesler equation of state. (H – Hig)0/RTc uses ω = 0.0, and (H – Hig)1/RTc is the correction factor for a hypothetical compound with ω = 1.0. Divide by reduced temperature to obtain the enthalpy departure function.
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