What Role Do Catalysts Play in Chemical Reactions?
Catalysts aid chemical reactions by modifying their mechanism in a way that lowers the activation energy barrier. This barrier is the amount of energy that must be supplied for the reaction to take place. Although it is possible to take the opposite approach and supply more energy (for example, as heat), this may not be desirable due to cost, the danger of heating the reactants and the fact that increasing the temperature may result in undesirable products. For all these reasons, catalysts are widely used in chemical industries, such as petroleum refining. Types of Catalysts Catalysts are classified as homogeneous and heterogeneous. A homogeneous catalyst is one that is present in the same phase as the reactants–for example, gases–while a heterogeneous catalyst is present in a different phase. For example, the chlorofluorocarbons (CFCs) that catalyze the destruction of ozone do so as homogeneous catalysts because they are gases. In the Antarctic, solid ice microcrystals function as h
