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Unformatted text preview: 166 PHASE EQUILIBRIUM We showed at the beginning of this chapter that the equilibrium state of a system at a specified temperature and pressure is the state of the minimum Gibbs function, and the equilibrium criterion for a reacting or nonreacting system was expressed as (Eq. 164)
1dG2 T,P 0 FIGURE 1617 Wet clothes hung in an open area eventually dry as a result of mass transfer from the liquid phase to the vapor phase. Vol. OS36/PhotoDisc In the preceding sections we applied the equilibrium criterion to reacting systems. In this section, we apply it to nonreacting multiphase systems. We know from experience that a wet T-shirt hanging in an open area eventually dries, a small amount of water left in a glass evaporates, and the aftershave in an open bottle quickly disappears (Fig. 1617). These examples suggest that there is a driving force between the two phases of a substance that forces the mass to transform from one phase to another. The magnitude of this force depends, among other things, on the relative concentrations of t...
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- Summer '08