Chemistry Textbook

Speed plays an important role in many of the things we do in everyday life. You may use a favorite website for streaming video content online, because of its quick and reliable download speeds. Similarly, the speed of a chemical reaction is also a significant consideration and is called its reaction rate. Reaction rates play important roles in understanding many chemical processes- from the baking of a cake to determining the useful span of a bridge. The relative speeds of various reactions that occur during polymerization of the compound ethene (C₂H₄) determine the properties of plastic.

Some reactions occur on a time scale of seconds, while other reactions many take many days or even years to occur. For example, the reaction between carbon monoxide and oxygen is so slow that it cannot be observed in practical time at normal temperatures and pressures. However, inside an automobile's catalytic converter, the palladium coating and the high temperature enables this reaction to happen fast so that toxic carbon monoxide gas converts to less toxic carbon dioxide before being released into the atmosphere. To increase profits, industries heavily invest in the design of substances called catalysts, which speed up reactions that convert raw materials to useful products.

The study of chemical kinetics concerns the question, "How rapidly will a reaction occur?". Another useful question when investigating rate of reactions in greater detail is: “What specific molecular-level processes take place as the reaction occurs?” Knowing the answer to these questions is of practical importance when the yield or rate of a reaction needs to be controlled. This chapter examines the factors that influence the rates of chemical reactions, the detailed steps (mechanisms) by which reactions proceed, and the quantitative techniques used to describe the rates at which reactions occur.