Introduction

The energy given off in chemical reactions powers our cars, airplanes, and ships, heats our homes, cooks most of our food, and is the energy source of the generating plants that product most of our electricity. Our own bodies obtain the energy they need from chemical reactions in which the food we eat combines with oxygen from the air we breathe.

Not all chemical reactions liberate energy—some reactions must be supplied with energy in order to occur. Even those reactions that liberate energy may not take place unless some initial energy is furnished to start the process. Another aspect of chemical reactions is that they take time to be completed: a fraction of a second to many years, depending on a number of factors. Not all reactions even go to completion. Instead, an intermediate equilibrium situation often occurs with the products undergoing reverse reactions to form the starting substances just as fast as the primary reaction proceeds. These are some of the topics considered in this chapter.