The Frequency Factor for Outer-Sphere Electrochemical Reactions.
Abstract
The conventional formulation of the frequency factor (A sub (n)(e) for outer-sphere electrochemical reactions based on a 'collisional' model is compared with an alternative 'encounter preequilibrium' treatment whereby An is determined by the effective frequency of surmounting the free energy barrier within a previously assembled precursor state. The latter model is shown to provide a more appropriate description for electrochemical reactions under most conditions, in harmony with analogous considerations for homogeneous redox processes. Noticeably (ca. 20-fold) larger values of A sub n(e) are derived from the encounter preequilibrium as compared to the collisional model. Numerical relationships between the kinetics of corresponding electrochemical and homogeneous reactions and of competing inner- and outer-sphere electrochemical pathways that are significantly different from the conventional relations are also predicted on the basis of the encounter preequilibrium model. The relationships between A sub N(e) and experimental frequency factors obtained from the temperature dependence of electrochemical rate constants are also considered in the light of these considerations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1983
- Accession Number
- ADA126722
Entities
People
- Joseph T. Hupp
- Michael J. Weaver
Organizations
- Purdue University