#Chem 162-2008 10th week recitation truncated

# #Chem 162-2008 10th week recitation truncated - CHEMISTRY...

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CHEMISTRY 162-2008 10 th WEEK RECITATION TRUNCATED Ed Tavss, PhD ANNOUNCEMENTS E-MAIL ATTENDANCE Sign in EXAMS Exam II: How did we do? Virtually anyone can still get a B  (~255 pts used so far; ~445 pts left); QUIZ Pick up lecture quizzes and old quizzes after class. MISCELLANEOUS Chem 162-2008 10 th week recitation 1

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PLAN FOR TODAY : CHAPTER 17 - SPONTANEITY, ENTROPY AND FREE ENERGY Spontaneity, entropy and free energy Chemical reactions: Entropy changes and free energy Free energy: Pressure dependence and equilibrium Chem 162-2008 10 th week recitation 2 Rutgers/Pharmacy GRADES CHEM 162-2007 EXAM II SCORES SECTIONS AVERAGE TAVSS’ SECTIONS AVERAGE T T T
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 ΔS surr = -q rev /T = -ΔH system /T ΔG o = Σn p ΔG o f(products) - Σn r ΔG o f(reactants) ΔH o = Σn p ΔH o f(products) - Σn r ΔH o f(reactants) ΔS o reaction = Σn p S o products - Σn r S o reactants Three ways to find ΔG o : (1) ΔG o = ΔH o - TΔS o (or ΔG = ΔH - TΔS) (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) ΔG = ΔH - TΔS At equilibrium, 0 = ΔH - TΔS Only at equilibrium: ΔS system = ΔH system /T Trouton’s rule: At normal B.P., ΔS system = ΔH system /T ≈ 87J mol -1 K -1 w max = ΔG Chem 162-2008 10 th week recitation 3

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SPONTANEOUS PROCESS KINETICS vs. THERMODYNAMICS Gibbs Free Energy Domain of kinetics reactants products Domain of thermodynamics (e.g., ∆G, SPONTANEITY ) Chem 162-2008 10 th week recitation 4
SPONTANEOUS PROCESSES ET: Spontaneous doesn’t mean fast; it has nothing to do with speed. 16.15 (mod.) Which of the following processes are spontaneous?

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## This note was uploaded on 09/23/2009 for the course CHEM 162 taught by Professor Siegal during the Spring '08 term at Rutgers.

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#Chem 162-2008 10th week recitation truncated - CHEMISTRY...

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