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Unformatted text preview: a waterair interface are also different even when air is saturated (Fig. 1622). Therefore, when specifying mole fractions in two-phase mixtures, we need to clearly specify the intended phase. In most practical applications, the two phases of a mixture are not in phase equilibrium since the establishment of phase equilibrium requires the diffusion of species from higher concentration regions to lower concentration regions, which may take a long time. However, phase equilibrium always exists at the interface of two phases of a species. In the case of airwater interface, the mole fraction of water vapor in the air is easily determined from saturation data, as shown in Example 168. The situation is similar at solidliquid interfaces. Again, at a given temperature, only a certain amount of solid can be dissolved in a liquid, and the solubility of the solid in the liquid is determined from the requirement that thermodynamic equilibrium exists between the solid and the solution at the interface. The solubility repre...
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- Summer '08