Chapter 14 - Thermodynamic properties of ideal gases

Abstract

To this point, our study of statistical thermodynamics allows us to define the most parable macrostate for an isolated system of independent particles, and to introduce the mathematic definitions for internal energy and entropy. Having now available such information, we were able to present general analytical expressions for the remaining thermodynamic quantities of the ideal gas. We found that all the thermodynamic properties are functions of the partition function, which has information on the allowed energy levels and degeneracy of the translational, rotational, vibrational, and electronic energy modes. In this section, we investigate the thermodynamic quantities of the monatomic gases, in which we need to consider translational and electronic energy modes. Then we estimate the thermodynamics of diatomic gases, first, in the simplex model that requires to consider not only the translational and the electronic modes but also the vibrational and rotational energy modes. For an accurate calculation, a complex model must replace the simplex model. Finally, we present the thermodynamics of the polyatomic gas.