surface chemistry

surface chemistry,

study of chemical reactions in which the reactants are first adsorbed onto a surface medium (see adsorptionadsorption,
adhesion of the molecules of liquids, gases, and dissolved substances to the surfaces of solids, as opposed to absorption, in which the molecules actually enter the absorbing medium (see adhesion and cohesion).
..... Click the link for more information. ) that then acts as a catalystcatalyst,
substance that can cause a change in the rate of a chemical reaction without itself being consumed in the reaction; the changing of the reaction rate by use of a catalyst is called catalysis.
..... Click the link for more information. for the reaction; after the reaction the products are desorbed and the surface is left unchanged. Since the entire reaction takes place on the surface, the amount of surface area of catalyst per unit weight determines the effectiveness of the surface in the reaction. Some silica surfaces have over 200 square meters of surface area per gram. An example of a surface reaction is the reaction of an unsaturated organic molecule with hydrogen on finely divided platinum or with bromine on finely divided silica. Enzymeenzyme,
biological catalyst. The term enzyme comes from zymosis, the Greek word for fermentation, a process accomplished by yeast cells and long known to the brewing industry, which occupied the attention of many 19th-century chemists.
..... Click the link for more information. reactions can, in principle, also be considered surface reactions, since the reaction takes place on the enzyme surface after the enzyme has bound the reactants; however, usually only heterogeneous (two-phase) reactions are considered true surface reactions, while enzyme reactions are homogeneous (one-phase) systems.