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Unformatted text preview: ive properties of each phase (except their relative amounts) are fixed. Therefore, a single-component two-phase system has one independent property, which may be taken to be the temperature or the pressure. In general, the number of independent variables associated with a multicomponent, multiphase system is given by the Gibbs phase rule, expressed as
IV C PH 2
(1620) LIQUID WATER WATER VAPOR T 100C 150C 200C . . . where IV the number of independent variables, C the number of components, and PH the number of phases present in equilibrium. For the single-component (C 1) two-phase (PH 2) system discussed above, for example, one independent intensive property needs to be specified (IV 1, Fig. 1619). At the triple point, however, PH 3 and thus IV 0. That is, none of the properties of a pure substance at the triple point can be varied. Also, based on this rule, a pure substance that exists in a single phase FIGURE 1619 According to the Gibbs phase rule, a single-component, two-phase system can have...
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- Summer '08