Brief overview of chemistry kinetics

Chemistry Kinetics

This section gives a brief overview of the subject area of the simulations. It's designed to give non-chemists a flavour of the subject.
Reaction kinetics provides insight into the actual mechanisms of chemical reactions, not just the reactants and products, but the details of the transformation from one set of chemical species to another. It involves the study of the chemical reaction process through the measurement of the rate with which a reaction proceeds and the dependence of this reaction rate on the concentrations of reacting species and the temperature.

It is not possible to predict the rate of a reaction, as reactions do not proceed directly from reactants to products, but usually involve a number steps. The rate of a reaction and the factors affecting the rate must be determined experimentally. These results are summarised for a given reaction by a rate equation that is usually of the form

Rate = k x function of the concentration of reagents

where k is the rate constant and is dependent on temperature (T) according to the empirical relationship

k = Ae^-E0/RT

where A is the pre-exponential factor, E0 is the activation energy and R is the gas constant.

It has been found that a large number of reactions have rates that at a given temperature are proportional to the concentration of one or two of the reactants raised to a small integral power, known as first, or second reactions respectively.

Rate = k[A] (1st order)

Rate = k[A]2 or Rate = k[A][B] (2nd order).

A zeroth order reaction is also possible where the rate of reaction does not depend on how much reactant is present.