Chp4_Fig8b

# Chp4_Fig8b - Figure 4.8(b in CAQS The reaction described is...

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Figure 4.8(b) in CAQS The reaction described is the generic: ) ( ) ( g X g W . Assume T = 298 K . The stoichiometry is such that the total pressure is constant; that is, when some amount of W(g) is consumed, the same amount of X(g) is formed and vice-versa. The figure suggests that, for simplicity: atm p p X W 1 = + To supply some actual values, let us assert that: mol kJ G mol kJ G X W / 23 / 22 = = These values could be obtained as delta G of formation for X, W for actual molecules. In the text figure, we are simply given the value of K in the figure text but I wanted to illustrate for you how one might compute K from other information provided or available from tables. For our reaction, then: mol kJ G G G W X rxn / 00 . 1 + = - = . Then, 67 . 0 exp ln = - = - = RT G K K RT G rxn rxn Please note: rxn G is the “chemical force” acting upon the reaction IF one were to have BOTH W(g) and X(g) present; unmixed; and in their standard states (at 1 atm). This actual composition appears NOWHERE on our figure. Where we have W p =1.0 atm on the figure has X p = 0.0 atm. Bullet one notwithstanding, the value of rxn G tells us something about the equilibrium composition; more specifically, the value of K, the equilibrium

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## This note was uploaded on 03/30/2008 for the course CH 201 taught by Professor Warren during the Fall '07 term at N.C. State.

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Chp4_Fig8b - Figure 4.8(b in CAQS The reaction described is...

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