Ionic Equilibria in Mixed Solvents. IV. Solvent Effect on Dissociation Constants of Acids

Publisher Website
Google Scholar
Abstract
Equilibrium of hydronium ions with alkoxonium ions in water-alcohol mixtures being taken into account, solvent effects on dissociation constants of acids were quantitatively interpreted by the following: free energy changes on transferring ions from an aqueous solution to a mixed solvent and difference in standard states in different solvent compositions. Choosing suitable values for effective ionic radii for ions involved, satisfactory agreements were found between experimental and calculated values of ΔpK, the difference of pK in water and in an aqueous mixture, for positively charged acids (e.g., ammonium, anilinium, etc.) as well as neutral acids yielding a negatively charged conjugate base (e. g., acetic acid, benzoic acid, p-nitrophenol, etc.).