SOLVENT EFFECTS ON THE DISSOCIATION OF WE AK ACIDS IN WATER-ETOH MIXTURES AT 298.15K

The ionization enthalpies of acetic, chloroacetic, bromoacetic, iodoac etic, propionic and n-butyric acids in water-EtOH mixtures were measur ed at 298.15K with an LKB 2277 Bioactivity monitor. The values of free energy and entropy of ionization were then calculated. On the base of experimental data, the free energy changes on transfer of carboxylate ions from water to water-EtOH mixtures for the studied acids were obt ained according to the procedure givin in the literatures. The solvent effects on the ionization of the six weak acids were discussed in det ail.