Activation Volumes for the Hydration Reactions of Carbon Dioxide

Abstract

The hydration of CO2(aq) via reaction with H2O and OH– has been investigated using a high-pressure stopped flow apparatus, and the relevant rate constants for the reactions have been determined using a global analysis approach. The joint analysis of a series of kinetic measurements, for the formation and decomposition reactions, at a range of pressures from 400 to 1000 atm has been performed, and from the pressure dependence of the rate constants, the corresponding activation volume profiles determined for the two kinetic pathways. While a previous report exists for the hydration reaction with water, to our knowledge the activation volumes for the reaction of CO2 with hydroxide in this paper are the first to be reported in the literature. The extensive measurement data and robustness of the analysis approach, which additionally incorporates into, and corrects for, the effect of ionic strength on the kinetic data, positions the current data as the most reliable to date.