Brian C. Dunn

Abstract: A program has been developed for the implementation of a mathematical treatment which corrects for a concentration gradient within the stopped-flow observation cell for reversible second-order reaction kinetics studied by longitudinal absorbance measurements This program has been tested using experimental kinetic data for three selected electron-transfer cross reactions with predicted rate constants of 11 × 106, 58 × 107, and 12 × 108 M-1 s-1, respectively A second gradient-corrected approach has also been applied based on the steady-state absorbance which exists after the flow tube has been filled with the new reaction mixture just prior to the stopping of the flow (a permutation of the continuous-flow method) As a third comparison, the same data were also analyzed using a standard reversible second-order kinetic treatment, without corrections for the concentration gradient, by applying an appropriate time base correction The experimental kinetic data were obtained using an unmodified commercial s