Unformatted text preview: ressure of 0.1 MPa. On this diagram, the vapor line represents the equilibrium composition of the vapor phase at various temperatures, and the liquid line does the same for the liquid phase. At 84 K, for example, the mole fractions are 30 percent nitrogen and 70 percent oxygen in the liquid phase and 66 percent nitrogen and 34 percent oxygen in the vapor phase. Notice that
y f,N2 y g,N2 y f,O2 y g,O2 0.30 0.66 0.70 0.34 1 1
(1621a) (1621b) Therefore, once the temperature and pressure (two independent variables) of a twocomponent, twophase mixture are specified, the equilibrium composition of each phase can be determined from the phase diagram, which is based on experimental measurements. It is interesting to note that temperature is a continuous function, but mole fraction (which is a dimensionless concentration), in general, is not. The water and air temperatures at the free surface of a lake, for example, are always the same. The mole fractions of air on the two sides of a waterair interface, however, are obviously very different (in fact, the mole fraction of air in water is close to zero). Likewise, the mole fractions of water on the Chapter 16
two sides of...
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 Summer '08
 HAJISHEIK
 Thermodynamics, Equilibrium, Combustion, Chemical reaction, equilibrium composition

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