The rate of a chemical reaction is typically specified as the rate of formation of a particular product of the reaction or the rate of disappearance of a particular reactant. These two rates are the same for some reactions, such as those in which the reaction of every molecule of a particular reagent leads to the production of one molecule of a particular product. Many reactions are more complex and are characterized by different rates for the different species involved in the reaction.

In order to be able to predict the rate of a reaction, the affect of changing the concentrations of each species involved in the reaction is determined experimentally. The experimental information is summarized in an equation called the rate law for the reaction. It expresses the change in concentration of a particular species as a function time in terms of the concentration, or...