SOLVENT EFFECTS ON THE DISSOCIATION REACTIONS OF TARTARIC, MALEIC ANDPHTHALIC ACIDS - COMPARATIVE-STUDY AND ANALYSIS OF THERMODYNAMIC FUNCTIONS

The first and second dissociation constants of tartaric, maleic and ph thalic acids have been determined using EMF method in water-ethanol mi xed solvents, over a wide range of solvent composition (0-60 wt% ethan ol) at six different temperatures (ranging from 30 to 55 degrees C at intervals of 5 degrees C). The thermodynamic parameters (Delta G degre es, Delta H degrees and Delta S degrees) for the first and the second ionization reactions were calculated from the well known equations. Th e results have been discussed in terms of the solute-solvent interacti ons and were compared with those of malic, malonic and succinic acids in the same mixed solvents. (C) 1997 Elsevier Science B.V.