KINETICS AND THERMODYNAMICS OF ION-MOLECULE ASSOCIATION REACTIONS OF WATER, HYDROGEN-SULFIDE, AND BENZENE - COMMENTS ON INTER-MOLECULAR ENTROPY EFFECTS

Rates of three-body ion-molccule association reactions of the type A++ B + M → AB++ M have been calculated.A critical assumption in the analysis is that the internal energy of the collision complex formed from A+and B is randomized; RRKM theory is used to model the decomposition of the collision complex back to reactants. The formation of the protonbound dimers of H2O and H2S is examined, as is the formation of the benzene dimer radical cation, (C6H6)2+. Agreement with experimental kinetic data is good. Applications of this analysis to obtaining thermodynamic data for ion molecule reactions from experimental kinetic data arc considered. Finally, the suggestion that nonideal contributions to ΔS for ion-moleculc reactions may be significant is discussed critically. © 1979, American Chemical Society. All rights reserved.