TABLE OF CONTENTS The main reasons for measuring rates of reactions are: (i) to obtain information about the reaction mechanism, which may prove useful in modifying the course of that reaction or in predicting the behaviour of similar, as yet untested, reactions; and/or (ii) to determine values of the kinetic parameters (see below) for the reaction of interest, which may allow rates of reaction under conditions of reaction different from those for which the measurements were made, to be calculated by interpolation or (with less certainty) extrapolation.
These two aims are seldom unrelated, because the reaction mechanism, which is used here in the sense of the detailed chemical steps involved, can usually only be inferred from the overall picture constructed from the results of the mathematical side of kinetic analysis (the kinetic model) and as much complementary evidence (e.g., spectroscopy, chemical and structural analysis, etc.) as possible.
The rate of a general homogeneous reaction of the form:
is conventionally measured by following the decrease in concentration of reactant A or the increase in concentration of either product B or C at constant temperature. A rate equation of the form:
is then determined from experiment. The rate coefficient, k, is a function of temperature, usually assumed to be given by the Arrhenius equation [1]:
where T is the temperature in kelvin, and the Arrhenius parameters, E the activation energy and A the pre-exponential or frequency factor, can be determined by carrying out a...
