Thermodynamic Properties of high temperature air components

The paper gives a synthetic description of the basic methods to calculate the high-temperature thermodynamic properties of air species. Emphasis is given to the strong dependence of the electronic partition function and the thermodynamic properties of atomic species on the number of electronic levels taken into account. The specific heat of the diatomic species presents a maximum followed by a steep decrease towards zero. This effect, which is usually not reported in standard textbooks of statistical thermodynamics, is a direct consequence of the finite number of energy levels accounted for in the internal partition function. A similar effect exists also for the atoms.