Unformatted text preview: UM CONSTANT FOR IDEAL-GAS MIXTURES Consider a mixture of ideal gases that exists in equilibrium at a specified temperature and pressure. Like entropy, the Gibbs function of an ideal gas depends on both the temperature and the pressure. The Gibbs function values are usually listed versus temperature at a fixed reference pressure P0, which is taken to be 1 atm. The variation of the Gibbs function of an ideal gas with pressure at a fixed temperature is determined by using the definih T s 2 and the entropy-change relation tion of the Gibbs function 1 g R u ln 1P2>P1 2 4 . It yields for isothermal processes 3 s
1 g 2 T 0 h T 1 s 2 T T 1 s 2 T R uT ln P2 P1 Thus the Gibbs function of component i of an ideal-gas mixture at its partial pressure Pi and mixture temperature T can be expressed as
g i 1T, Pi 2 gi* 1T2 RuT ln Pi
(1610) Chapter 16
sure and temperature T, and Pi represents the partial pressure of component i in atmospheres. Substituting the Gibbs function expression for each component into Eq. 169, we obtain
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This note was uploaded on 06/15/2009 for the course MAE 3311 taught by Professor Hajisheik during the Summer '08 term at UT Arlington.
- Summer '08