Chapter 20 Lecture 1

Chapter 20 Lecture 1 - Chapter 20 Thermodynamics: Entropy,...

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Chapter 20 Thermodynamics: Entropy, Free Energy and the Direction of Chemical Reactions 20-1
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Thermodynamics: Entropy, Free Energy, and the Direction of Chemical Reactions 0 1 he Second Law of Thermodynamics: 20.1 The Second Law of Thermodynamics: Predicting Spontaneous Change 20.2 Calculating the Change in Entropy of a Reaction 20.3 Entropy, Free Energy, and Work 20.4 Free Energy, Equilibrium, and Reaction Direction 20-2
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20.1 The Second Law of Thermodynamics pontaneous changes Spo ta eous c a ges – occur without any external influence Examples: Aging, rusting, heat transfer from hot to cold, expansion of gases into vacuum, etc. Nonspontaneous changes – require an external force or energy in order to occur xamples: efrigeration (heat transfer from cold to hot), Examples: Refrigeration (heat transfer from cold to hot), evacuation of flasks by vacuum pumps, etc. If a process is spontaneous in one direction, it is not pontaneous in the other spontaneous in the other Example : At -20°C, water freezes spontaneously, but ice does not melt spontaneously: H O(l) H O(s) spontaneous 2 () 2 () p H 2 O(s) H 2 O(l) nonspontaneous Spontaneous does not mean “instantaneous” 20-3 It has nothing to do with how long a process takes to occur – Example: rusting and aging (spontaneous but slow)
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Limitations of the First Law of Thermodynamics
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This note was uploaded on 07/31/2010 for the course CHEM CHEM 01C taught by Professor Unknown during the Spring '10 term at UC Riverside.

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Chapter 20 Lecture 1 - Chapter 20 Thermodynamics: Entropy,...

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