THERMODYNAMIC STUDIES ON THE DISSOCIATION REACTIONS OF SUCCINIC, MALONIC AND MALIC-ACIDS IN ETHYL ALCOHOL-WATER MEDIA

The first and second dissociation constants of succinic, malonic and m alic acids have been determined by a precise EMF method in water and i n aqueous binary mixtures of ethyl alcohol, over a wide range of solve nt composition (0-60 wt% ethyl alcohol). Measurements were made at six different temperatures (ranging from 30 to 55 degrees C at intervals of 5 degrees C). The thermodynamic properties (Delta G degrees, Delta S degrees and Delta H degrees) for the first and second dissociation r eactions of these acids were computed, analysed and discussed in terms of solute-solvent interactions. Delta H degrees-Delta S degrees, Delt a S degrees-Delta G degrees and Delta G degrees-Delta H degrees correl ations among different solvent media were examined. The pK value has b een correlated with the dielectric constant of the medium according to Born's equation.