Unified analytical formulation regarding thermodynamic properties subject to gaseous metal hydroxides

Abstract

Analytical formulations concerning the Gibbs free energy for simple substances and compounds show important applications in dealing with many issues, but acquiring such a formulation with few adjustable parameters remains a challenging goal. Here, we report a unified analytical formulation regarding the Gibbs free energy subject to gaseous metal hydroxides MOH for (M=Al, Be, Cs, K, Li, Mg, Na, Sr, and Ca). It depends only on experimental data of atomic masses and six molecular constants except for an adjustable dimensionless pure number, while the temperature-dependent Gibbs free energy polynomial correlation provided in the National Institute of Standards and Technology (NIST) Chemistry WebBook has eight adjustable coefficients, which take different values in different temperature ranges for each species. The mean relative errors between the predicted Gibbs free energy values subject to nine metal hydroxides and the NIST data are within the range of 0.012 % to 0.078 %, and the predicted results of entropy, enthalpy and isobaric heat capacity are also in good agreement with the NIST data. The proposed unified model possesses the characteristics of high prediction accuracy and strong flexibility.