Thermodynamics%20Outline%20F07

Thermodynamics%20Outline%20F07 - Chapter 19 Thermodynamics...

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Chapter 19 Thermodynamics (A Brief Overview) (To help you with end-of-chapter problems) Enthalpy Change Δ H is a measure of the energy difference between products and reactants. In exothermic reactions, the products are energetically more stable than the reactants. Δ H < 0 is favorable for spontaneity. Δ H ° = Σ n Δ H ° f (products) - Σ n Δ H ° f (reactants) Enthalpy of formation values for substances are listed in Appendix C. Entropy Change Δ S is a measure of the entropy difference between products and reactants. An increase in entropy leads to a more random and disordered (and more probable) state. Δ S > 0 is favorable for spontaneity. The sign of Δ S can be determined by analyzing the molecular-level differences in entropy between reactants and products: (in order of importance) 1. Gases >> liquids > Solids 2. Greater number gas particles > Fewer number of gas particles 3. Mixtures (Solutions) > Pure Substances (that make of the mixture) 4. Compounds > Elements A value of Δ
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This note was uploaded on 01/27/2010 for the course CHM 71476 taught by Professor Marks during the Spring '10 term at ASU.

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Thermodynamics%20Outline%20F07 - Chapter 19 Thermodynamics...

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