Linear free energy relationship and some quantitative regularities of the of pressure on chemical reactions

Abstract

A study has been made of the applicability of a linear free energy relationship describing the effect of pressure on the equilibrium and rate constants of chemical reactions. Some properties of the relationship have been analysed and corollaries, including linear dependences, obtained which make it possible to calculate reaction enthalpies and entropies, volume changes and Hammett's p-constants at high pressures. Ionization reactions have been used as examples to illustrate the conclusions arrived at. The linear free energy relationship has been shown to describe the effect of pressure up to 8000 bars on the ionization constants of acids and on the pH of buffer solutions.