Chem 162-2008 10th week recitation formula page

Chem 162-2008 10th week recitation formula page - Σn r ΔH...

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CHAPTER 16 - SPONTANEITY, ENTROPY AND FREE ENERGY First law of thermodynamics: Energy can neither be created nor destroyed. Second law of thermodynamics: The entropy of the universe always increases in any spontaneous process. Third law of thermodynamics: The entropy of a perfectly ordered crystalline substance at 0 K is zero. Entropy describes the number of arrangements (positions and/or energy levels) available to a system. Entropy is (officially called chaos, disorder, randomness) positional freedom, or positional availability, or disorder, or being unconfined positionally or escape from positional confinement or freedom from positional confinement ΔG o = Σn p ΔG o f(products) - Σn r ΔG o f(reactants) ΔH o = Σn p ΔH o f(products)
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Unformatted text preview: - Σn r ΔH o f(reactants) ΔS o system = Σn p S o products- Σn r S o reactants ΔS system = Σn p S products- Σn r S reactants ΔS surr = -ΔH system /T = ΔH surr /T ΔS univ = ΔS sys + ΔS surr Three ways to find ΔG o : (1) ΔG o = ΔH o- TΔS o (or ΔG = ΔH - TΔS) At equilibrium ΔG = 0 0 = ΔH - TΔS) ΔS system = ΔH system /T Trouton’s rule: At normal B.P., ΔS system = ΔH system /T ≈ 87J mol-1 K-1 (2) ΔG o = Σn p ΔG o f(products)- Σn r ΔG o f(reactants) (3) ΔG 1 o + ΔG 2 o = ΔG T o (i.e., adding equations [Hess’s law]) ΔG = ΔG o + RT ln(Q) (Q can be pressure or concentration) At equilibrium, ΔG = 0 0 = ΔG o + RT ln(K) ΔG o = -RT ln(K) w max = ΔG...
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