Estimation of internal energy, enthalpy, and entropy, based on group contribution method and cubic equation of states

By utilizing a group contribution method (GCM) by specifying the number of functional groups forming the molecules, estimation of some of the pivotal properties of substances becomes feasible. To broaden the scope of the predictable properties and to expand the applicability of the GCM procedure, it may be required to combine it with an equation of state. In this work, the internal energy, enthalpy, and entropy in 2000 states per material of 69 compounds from the NIST database were compared with the results of 25 different GCM-based cubic equations of state and analyzed by classes of compounds to identify the limitations of the method and to suggest the use of an equation of state for each type of compounds. Interestingly, equations that depend on fewer material properties tend to yield better results, especially when those properties can be estimated with high precision. In contrast, equations that rely on more parameters may be more sensitive to inaccuracies in property estimates, making them less reliable. • U, H and S are calculated for 69 materials using 25 GCM-based cubic equations • Limitations arising from the inaccuracy of property estimation is determined • Equations depending on fewer material properties tend to yield better results • Clausius equation excels in eleven material groups but falls short in four.