EXTREMES IN DEPENDENCES OF ENTHALPY AND ENTROPY OF SATURATED VAPOR ONTEMPERATURE

It was proved that the enthalpy of saturated vapour as a function of t emperature has a maximum for all substances. The dependence of the ent ropy of saturated vapour on temperature can be monotonous, has a minim um and a maximum, or has only a maximum. The thermodynamic relations w ere derived for the existence of the extremes which enable their compu tation from the knowledge of dependence of the ideal-gas heat capacity on temperature and an equation of state. A method based on the theore m of corresponding states was proposed for estimating the extremes, an d its results were compared with literature data. The agreement betwee n the literature and estimated temperatures corresponding to the extre mes is very good. The procedure proposed can serve for giving precisio n to the H-l, and T-S diagrams commonly used in applied thermodynamics .