Thermodynamische Fundamentalgleichungen und charakteristische Funtionen

According to J.W. Gibbs, all thermodynamic properties of a fluid phase can be calculated from a single fundamental equation of state. Such an equation can be constructed with different pairs of independent properties and their proper characteristic functions. The thermodynamic theory of the characteristic functions and their selection for the use in a fundamental equation is discussed. Only two characteristic functions are suited for the analytical representation of the complete range of all fluid states: the Massieu-function (or the equivalent Helmholtz-function) as a function of temperature and volume, and the enthalpy as a function of pressure and entropy. The methods suited for establishing a fundamental equation with the dimensionless Massieu-function are described. A historical retrospect concerning the origin and the further development of fundamental equations and characteristic functions is presented.