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 h ave 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 ac id at 298.15K. These data are analysed taking into account an incomplete di ssociation of weak acids in aqueous solutions. Experimental concentration d ependence of Delta H-s can be satisfactorily described by the find equation which contains two enthalpy terms, characterising the ionic association pr ocess: Delta H(Al)degrees and Delta H(A2)degrees. The standard changes of e nthalpy associated with the first of them are presented. Method for determi nation of the standard dissolution enthalpy, Delta H(s)degrees, of weak asy mmetric electrolytes is also considered. (C) 1999 Elsevier Science B.V. All rights reserved.