Читать книгу Geochemistry - William M. White - Страница 86

Species is somewhat more difficult to define than either phase or component. A species is a chemical entity, generally an element or compound (which may or may not be ionized). The term is most useful in the context of gases and liquids. A single liquid phase, such as an aqueous solution, may contain a number of species. For example, H₂O, H₂CO₃, , , H⁺, and OH^– are all species commonly present in natural waters. The term species is generally reserved for an entity that actually exists, such as a molecule, ion, or solid, at least on a microscopic scale. This is not necessarily the case with components, as we shall see. The term species is less useful for solids, although it is sometimes applied to the pure end-members of solid solutions and to pure minerals.