Influence of non-uniform concentration of reactants on the apparent rate constant of first-order and second-order reactions as determined by optical absorption

Abstract

Variation in the initial concentration of reactant along the light path has no effect on first-order plots and, for practical values of the parameters, causes only a small increase in the estimate of rate constants for second-order plots. Variation of concentration across the light path slightly decreases the estimate of k for first-order plots and can become important for second-order plots. For the values of the several parameters normally used, however, the errors are small and can be estimated from the formulae and curves presented.