Collect. Czech. Chem. Commun. 1983, 48, 2156-2164

Autoprotolysis constants and activity ratios of the lyate ions in water-alcohol mixtures

Jiří Mollina, Zdeněk Paveleka, Alena Schneiderováa, Jaroslav Vičarb, Vilím Šimánekb and Jan Lasovskýa

a Department of Inorganic and Physical Chemistry
b Department of Medical Chemistry, Palacký University, 771 46 Olomouc


The autoprotolysis constants were determined potentiometrically for water-ethanol, water-1-propanol, water-2-propanol, and water-2-methyl-2-propanol mixtures containing alcohol in concentrations of 60% (m/m) and more. Three methods were employed for the calculation of the activity ratios of the lyate ions in the systems: an empirical method based on the autoprotolysis constant and the activities of the solvent constituents, a method based on thermodynamic data, particularly the Gibbs energies of ion transfer from water to the mixed solvent, and a method based on 1H NMR data. The results of the three methods are mutually compared and discussed. The known heats of ionization for the water-ethanol system and the ionization constants of the components enabled the entropy of ionization of a mixture of water with ethanol to be calculated.