Theoretical prediction of Gibbs free energy and specific heat capacity of gaseous molecules

Abstract

• Highly efficient equations for the prediction of molar Gibbs free energy and molar specific heat capacity are presented. • The equations are based on the improved generalized Pöschl-Teller oscillator. • The analytical models are applicable to large class of diatomic and triatomic molecules. • The equations require only three molecular constants of the molecule as input data. Using the improved generalized Pöschl-Teller oscillator to model the internal vibration of a diatomic molecule, analytical equations to predict molar Gibbs free energy and specific heat capacity at constant pressure were obtained. The equations were applied to ground-state Br 2 , Cl 2 diatomic molecules, and CO gaseous molecule. Average absolute deviations of 0.0755%, 0.0787%, and 0.3583%, were obtained using the equation of reduced molar Gibbs free energy. The expression of molar specific heat capacity yielded average absolute deviations of 4.5055%, 2.5308%, and 2.3665%, respectively from experimental data for the diatomic molecules. The results are in good agreement with existing literature data on the diatomic molecules.