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

Enthalpies of dissolution, Delta H-s, of malonic and maIic acids in water have been determined at molalities ranging from 4 x 10(-3) to about 29 x 10(-3) for malonic acid and from 2 x 10(-3) to about 180 x 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 Delta H-s can be satisfactorily described by the find equation which contains two enthalpy terms, characterising the ionic association process: Delta H(Al)degrees and Delta H(A2)degrees. The standard changes of enthalpy associated with the first of them are presented. Method for determination of the standard dissolution enthalpy, Delta H(s)degrees, of weak asymmetric electrolytes is also considered. (C) 1999 Elsevier Science B.V. All rights reserved.