Method of analysis of data from measurements of heat of dissolution for some dicarboxylic acids at 298.15K

Abstract

Abstract Enthalpies of dissolution, ΔHs, of malonic and malic acids in water have been determined at molalities ranging from 4 × 10−3 to about 29 × 10−3 for malonic acid and from 2 × 10−3 to about 180 × 10−3 for malic acid at 298.15K. These data are analysed taking into account an incomplete dissociation of weak acids in aqueous solutions. Experimental concentration dependence of ΔHs can be satisfactorily described by the final equation which contains two enthalpy terms, characterising the ionic association process: ΔHAI° and ΔHA2°. The standard changes of enthalpy associated with the first of them are presented. Method for determination of the standard dissolution enthalpy, ΔHs°, of weak asymmetric electrolytes is also considered.