The Solvent Properties of Water

Abstract

To point out that water existed on this planet long before life evolved is, of course, stating the obvious, but the uniqueness of water as the universal solvent is still not generally appreciated. Until not so many years ago experimental studies of the physical and inorganic chemistry of solutions were restricted almost completely to aqueous systems and solution theories were largely based on results so obtained. It was mainly Hildebrand and Scatchard who, together with their many colleagues, drew the attention of the scientific and technological world to the fact that solutions need not necessarily be aqueous, and that the study of other solvent media would be more likely to help in the elucidation of solvent—solute interactions in condensed phases. Ironically, though, the development of solution theories based on experiments performed with “simple” solvents has often led to generalized claims regarding the role of the solvent, irrespective of the fact that water does not conform to some or all of the predictions of such theories. Even now there is a widely held view that water need not in any way be treated as a unique substance, but that its somewhat nonconformist behavior as a solvent can be allowed for by the introduction of various specific parameters into the well-established equations which adequately represent the behavior of simple nonaqueous mixtures.