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Unformatted text preview: a two-phase equilibrium mixture of liquid ammonia (NH3) and water (H2O) is frequently used. Consider one such mixture at 40C, shown in Fig. 1627. If the composition of the liquid phase is 70 percent NH3 and 30 percent H2O by mole numbers, determine the composition of the vapor phase of this mixture. Solution A two-phase mixture of ammonia and water at a specified temperature is considered. The composition of the liquid phase is given, and the composition of the vapor phase is to be determined. Assumptions The mixture is ideal and thus Raoult's law is applicable. Properties The saturation pressures of H2O and NH3 at 40C are PH2O,sat 7.3851 kPa and PNH3,sat 1554.33 kPa. Analysis The vapor pressures are determined from FIGURE 1627 Schematic for Example 1611. PH2O,gas side PNH3,gas side y H2O,liquid side PH2O,sat 1T2 y NH3,liquid side PNH3,sat 1T2 Ptotal PH2O PNH3 0.30 17.3851 kPa2 2.22 kPa 1088.03 kPa 0.70 11554.33 kPa2 2.22 1088.03 The total pressure of the mixture is 1090.25 kPa Then the mole fractions in the gas phase are y H2O,gas side y NH3,gas side PH2O,gas si...
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- Summer '08