Analysis of the dependence on temperature of the acid dissociation constants for mono-carboxylic acids in water in terms of a two-stage mechanism

Abstract

The dependence on temperature of acid dissociation constants in water are examined for four systems. The final equation is based on a two-stage dissociation where the enthalpy terms are assumed to be independent of temperature. The relatively small overall enthalpy change for dissociation is shown to be a consequence of the enthalpy changes for the individual stages. The dependence of the overall heat-capacity quantity on temperature is marked, showing a minimum at a characteristic temperature. For acetic acid, the calculated dependence is in qualitative agreement with calorimetric data.