Electrochemical measurement of the rates of coupled electrochemical and chemical reactions by the potential step method

Journal Article · Mon Dec 01 04:00:00 EST 1986 · J. Electrochem. Soc.; (United States)

DOI:https://doi.org/10.1149/1.2108463· OSTI ID:6629604

Lessner, P; Winnick, J; Mc Larnon, F R; Cairns, E J

The kinetics of the aqueous polysulfide redox couple were investigated using a potential step technique in a solution 1M in S/sup o/ and 1.3M in total S/sup 2-/, at pH 12. The low overpotential region (-20 to +20 mV) on cobalt and platinum electrodes was investigated from 25/sup 0/ to 80/sup 0/C. The active species concentration was found to be several orders of magnitude lower than those of any of the major (poly)sulfide ions, and its temperature dependence corresponded to an E/sub a/ of about 10 kcal/mol. These results are consistent, with the active species being S/sub 2//sup -/. Deviations were found at temperatures above 45/sup 0/C between experimental data and the simple analytical form for the current response for an electrode reaction with one rate determining step. The results agree with a new model that considers two rate-determining steps, one of which is the reaction S/sub 4//sup 2-/ in equilibrium 2S/sub 2//sup -/. The rate constants for this reaction determined using this new model agree with those measured for similar reactions.

• Research Organization: Science Div., Lawrence Berkeley Lab., and Dept. of Chemical Engineering, Univ. of California, Berkeley, CA 94720
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6629604
• Journal Information: J. Electrochem. Soc.; (United States), Journal Name: J. Electrochem. Soc.; (United States) Vol. 133:12; ISSN JESOA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
400400* -- Electrochemistry
AQUEOUS SOLUTIONS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
COBALT
CURRENTS
DISPERSIONS
ELECTRIC CURRENTS
ELECTRIC POTENTIAL
ELECTROCHEMISTRY
ELECTRODES
ELEMENTS
KINETICS
MATHEMATICAL MODELS
MEDIUM TEMPERATURE
METALS
MIXTURES
PH VALUE
PLATINUM
PLATINUM METALS
QUANTITY RATIO
REACTION KINETICS
REDOX REACTIONS
SOLUTIONS
SULFIDES
SULFUR COMPOUNDS
TEMPERATURE DEPENDENCE
TRANSITION ELEMENTS