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**Unformatted text preview: **and recognizing that nA/V = [A], etc., to get
n C +n D −n A −n B K = K C æ RT ö , where P è P ø KC = [C ] n C [D ] n D . [A ] n A [B ] n B Also, by recalling that PA = xAP, where xA is the mole fraction of A and P is the total pressure at equilibrium, we can express the equilibrium constant in terms of mole-fractions Kx: P n C +n D −n A −n B , where K = Kx æ P ö P è ø nC nD x x K x = CA DB . xn xn A B
2 Chemical Equilibria in Solution: Consider the aqueous reaction nPP(aq) + nQQ(aq) W nRR(aq) + nSS(aq). If the standard state is taken to be a concentration of 1 mol dm–3 of solution (i.e., a 1 molar solution), the equilibrium constant used is KC, defined as follows: K = C (c R /c ) n R (c S /c ) n S , (c P /c ) n P (c Q /c ) n Q where the standard concentration, c° = 1 mol dm–3, is included only to ensure that KC is dimensionless. If the standard state is taken to be 1 mol kg–1 of solvent (i.e., a 1 molal solution), a more accurate representation is possible in terms of “activities.” Activities are similar to fugacities i...

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