Generalized correlations residual entropy

Generalized correlations are developed here for the residual enthalpy and residual entropy from Eqs. (4-48) and (4-49). Substitution for Z by Eq. (2-63) puts Eq. (4-48) into generalized form ... 

As the equations above show, ideal gas heat capacities and the residual properties H and S can be used to calculate enthalpy and entropy values of gases at any temperature and pressure. The residual properties can be calculated using the generalized correlations discussed in Section 1.9.16. 

Using the residual property estimations from the generalized correlations estimate the change of enthalpy and entropy of 1 mol of n-butane gas expanding from 15 atm and 447 K to 1 atm and 435 K. 

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