ABSTRACT
Chemical reactions involve the transformation of reactants into products. This necessarily involves the making and breaking of chemical bonds. How do we understand reactions? Why do some reactions happen while other reactions do not? This chapter introduces readers to the classification of reactions – under the frameworks of reduction-oxidation (redox) and acid–base theories – as a means of understanding both what happens and why reactions happen. The enthalpy of reaction (∆r H˚) is used as a tool for interrogating the (un)favorability of a reaction, from which general principles are drawn. To understand redox reactions, readers are introduced to oxidation numbers as a bookkeeping method for tracking the transfer of electrons. For acid–base reactions, Brønsted–Lowry and Lewis acid–base theories are presented. To supplement the main discussion of reactions, electrochemical cells, pH, and precipitation reactions are discussed as topics related to, and explained by, redox and acid–base theories.
