Characteristic properties of thermodynamic functions for the theory of localized and nonlocalized adsorption

Abstract

The maxima, minima, and inflection points of the thermodynamic functions are calculated from the theory of localized and nonlocalized adsorption. Experimental determinations of the molecular thermodynamic functions, which depend on temperature alone, are discussed. Existing empirical methods of determining monolayer capacity from entropies and isosteric heat are examined. The inflection point of isosteric heat or of differential entropy directly gives monolayer capacity within an error less then 5% for ordinary systems. Similar results obtained for the BET theory are given in the Appendix; it is noted that the inflection point of the isosteric heat occurs at the coverage θ = 1−2c−1.