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Introduction to Chemical Mixtures

Author(s): David R. Caprette, PhD

Water as a Solvent

Water may be the most versatile solvent known. It is capable of dissolving both acids and bases, nearly all biologically important molecules, and a wide range of organic (carbon-based) and inorganic substances. More substances will dissolve in water than in any other known solvent, and it is the most abundant liquid solvent on Earth. The behavior of drops of water provides a clue as to why it is such a versatile solvent.

Water exhibits a property known as surface tension. It will form round beads on a surface, rather than spread out into a film. On the other hand, a similar quantity of oil or ethyl alcohol spreads out on a surface. It may seem strange to think of a liquid as having structure. Nevertheless there must be some structure, that is, some special interaction among water molecules. A liquid consisting of molecules that do not interact at all would be expected to spread out on a surface in a layer one molecule thick.