Unified non-fitting explicit formulation of thermodynamic properties for five compounds

Abstract

The explicit formulations of the Gibbs free energy subject to the concerned species are useful to determine the conditions for minimizing the total Gibbs free energy of a system with a simple way. Here, we develop a unified non-fitting explicit formulation of the Gibbs free energy for five compounds, including N2O, ClBO, OBBr, HBO and HCN. The established Gibbs free energy formulation is correlative only with masses of atoms and experimental data of six molecular constants of triatomic molecules, and away from requirement of fitting a plenty of experimental spectroscopic data or calorimetric data in conventional empirical expressions. For five compounds under consideration, the average absolute deviations between the predicted Gibbs free energy values and the data provided in the National Institute of Standards and Technology (NIST) database are within the range of 0.098% to 0.146%. Employing the developed unified non-fitting Gibbs free energy formulation with high accuracy, the theoretically predicted values of the entropy, enthalpy, and isobaric heat capacity for the concerned five substances are acquired, and the coresponding average absolute deviations from the NIST data are within the ranges of 0.166% to 0.263%, 0.571% to 2.533%, and 1.059% to 1.936%, respectively.