TABLE OF CONTENTS From Chapter 3 all chemical reactions involve energy changes as a combination of activation energy and reaction energy. Whilst in some cases the heat of reaction is absorbed into the products and the reaction cools (endothermic reactions), most reactions evolve energy as heat (exothermic reactions), and sometimes as light and sound. When the heat liberated or absorbed cannot be accommodated by the surrounding environment hazards are presented which can result in material damage. This can arise because either the amount of energy (thermodynamics) or the rate of energy release due to the speed of reaction (reaction kinetics) is excessive. The aim therefore is to establish the thermal stability of the system and then to control the extent and rate of heat release so as to minimize risk from energetic hazards. Thousands of reactive hazards have been documented by Bretherick (see Bibliography). The present chapter provides an insight into the hazards and the basic precautions to control the risk.
Reactive chemical hazards may arise from the inherent properties of the chemicals handled, used or disposed of and/or from their admixture or processing.
A hazard may arise with a chemical because of its tendency to decompose spontaneously or to react violently on contact with other common chemicals, as illustrated in Figure 7.1. The case of pyrophoric chemicals is summarized in Chapter 6; some dangerous reactions of compressed gases are mentioned in Chapter 9; other cases are summarized here.
