THE DEPENDENCE OF ION, PROTON, WATER, AND ELECTRON TRANSPORT PROCESSES ON SOLVENT STRUCTURE IN AQUEOUS ELECTROLYTIC SOLUTIONS.
LITTLE (ARTHUR D) INC CAMBRIDGE MA
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Transport phenomena in water, such as ionic conduction and viscous flow, can be treated as rate processes and activation energies calculated by the method of Arrhenius. These activation energies are highly dependent on structural changes in liquid water. The rate-determining step for the mechanism of electrical conduction of aqueous solutions of strong 11 electrolytes as hole formation in the solvent. The process occurs in both the free, monomeric water and in the rarified Frank-Wen clusters. The activation energy of this process exhibits a maximum at about 4 C and a minimum at about 2,000 bars. Protons conduct largely by the Grotthuss mechanism in aqueous solution. At 1 atm. the ratedetermining step for this process is the rotation of H2O, or of H3O, but this step is so facilitated by increasing pressure and thereby breaking-up the water structure that by about 1,500 bars the proton flip, possibly by quantum mechanical tunnelling, becomes limiting. At 1 atm. the Grotthuss mechanism is confined to the free, rotatable, water monomers. The activation energy of the process decreases with increasing pressure or increasing temperature. Author