Popular in Principles of Chemistry II
Barbi Della Polla
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Popular in Chemistry
This 3 page Class Notes was uploaded by Barbi Della Polla on Friday February 13, 2015. The Class Notes belongs to CHM 112 at University of Miami taught by Vanessa Falcao in Spring2015. Since its upload, it has received 45 views. For similar materials see Principles of Chemistry II in Chemistry at University of Miami.
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Date Created: 02/13/15
Class 0204 Calculating AGO at 25 AGquot rxn ZnAGO fproducts C VI A no ILL Otherthan 25 C lassuming the changein AHO rxnand ASO rxnis negligible AGO AH AGOtotal AGOreaction 1 AGOreaction 2 AG 2 0 reaction reaction reaction Standard Free Energies of Formation f 0 is the change in free energy when 1 mol of a compound forms from its constituent elements in their standard states 0 The free energy of formation of pure elements in their standard states is zero What s Free about Free Energy o Is the maximum amount of energy released from a system that is available to do work on the surroundings For many exothermic reactions some of the heat released due to the enthalpy change goes into increasing the entropy of the surroundings so it is not available to do work 0 And eve some of this free energy is generally lost to heating up the surroundings Maximum work 505 k Free energy of an Exothermic t Reaction 2 C 2 H gt 5 C5graph1te2H2g CH W l W 49 CH4g A H 746 AH xn 746k 0 a g a h e I C Minimum heat lost A 50 tosurroundings241k A G is less than A H0 because some of the released heat energy is lost to increase the entropy of the surroundings Free Energy and Reversible Reactions 0 The change in free energy is a theoretical limit as to the amount of work that can be done 0 If the reaction achieves its theoretical limit it is a reversible reaction Class 0204 RealReacUons Some if not most of the free energy is quotlostquot as heat Therefore real reactions are irreversible