The rate of a chemical reaction is, perhaps, its most important property because it dictates whether a reaction can occur during a lifetime. Knowing the rate law, an expression relating the rate to the concentrations of reactants, can help a chemist adjust the reaction conditions to get a more suitable rate. If there are two competing reactions for a single reagent, one can, knowing the rate law, favor the exclusive formation of a single product.

To obtain this kind of knowledge about reactions, we will first define what rate means. We will then derive the rate law expression. Using the method of initial rates, we will discuss how to determine the form and order of the rate law. Next, we will probe rate laws in depth and introduce the integrated rate law as an alternative form of the simple rate law that allows us another, more simple, experimental method to determine the order of the rate law. The integrated rate law will also allow us to determine the half-lives of chemical reactions.