Lecture11 - Electrochemistry Chemical Change and Electrical Work 21.1 Half-Reactions and Electrochemical Cells 21.2 Voltaic Cells Using Spontaneous

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1 Chapter 21 Electrochemistry: Chemical Change and Electrical Work Electrochemistry: Chemical Change and Electrical Work 21.1 Half-Reactions and Electrochemical Cells 21.2 Voltaic Cells: Using Spontaneous Reactions to Generate Electrical Energy 21.3 Cell Potential: Output of a Voltaic Cell 21.4 Free Energy and Electrical Work 21.5 Electrochemical Processes in Batteries 21.6 Corrosion: A Case of Environmental Electrochemistry 21.7 Electrolytic Cells: Using Electrical Energy to Drive a Nonspontaneous Reaction Basic Lessons/Concepts • Oxidation Numbers Æ electron book keeping • Identifying Redox reactions Æ Changes in ox. numbers • Electrochemistry = Redox chemistry at electrodes • The ability to separate chemical reagents and control electron transfer = ability to store and control release of chemical potential energy (batteries, electrolysis) • Electrons flow in direction of spontaneous rxn (release stored chemical potential energy) Æ cell potential • Reduction potentials tabulated relative to a standard reference (hydrogen electrode) • Cell potentials are fundamentally related to the reaction free energy ( Δ G…spontaneity, max. work, equilibrium constants) • Nonspontaneous reactions can be driven with external energy source (by doing work on system) Æ electrolysis (fuels, separation of materials, storing energy…) Review of Previous Lecture 1. Spontaneity of Electrochemical Reactions Δ G < 0 Æ E > 0 ….reation is spontaneous as written Δ G = -nFE (max. work mol -1 ) Æ Δ G = Δ G 0 +RTlnK eq ; E = E 0 –RTlnK eq /nF Δ G=0 at equil AND E = 0 (dead battery) at equil Æ E 0 = RTlnK eq
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This note was uploaded on 04/18/2011 for the course CHM 151 taught by Professor Dong during the Winter '08 term at University of Toronto- Toronto.

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Lecture11 - Electrochemistry Chemical Change and Electrical Work 21.1 Half-Reactions and Electrochemical Cells 21.2 Voltaic Cells Using Spontaneous

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