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MIT OpenCourseWare http://ocw.mit.edu 5.111 Principles of Chemical Science Fall 2008 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms .
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26.1 5.111 Lecture Summary #26 Oxidation/Reduction Lecture 3 Topics: Adding and Subtracting Half-Cell Reactions, and Nernst Equation Chapter 12 From Friday’s handout Standard States and Cell Potentials = cell -n E ° cell E ° cell = cell potential (cell voltage) in which products and reactants are in their standard states Units for E is volts. Example - Calculate E ° cell for Zn (s) | Zn 2+ (aq) || Cu 2+ (aq) |Cu (s) anode Zn (s) Zn 2+ (aq) + 2e - Zn (s) (oxidation) cathode Cu 2+ (aq) + 2e - Cu (s) (reduction) E °(cell) = standard reduction potential minus standard reduction potential for the couple at cathode for the couple at anode E °(cell) = E °(cathode) - E ° (anode) Look up Standard REDUCTION Potentials ( E °) in back of book (measured against S.H.E) Zn 2+ (aq) + 2e - Zn (s) = -0.7628 volts Cu 2+ (aq) + 2e - Cu (s) = +0.3402 volts E °(cell) = E °(cathode) - E ° (anode) E ° (Cu 2+ /Cu(s)) - E °(Zn 2+ /Zn(s)) = 0.3402 - (-0.7628 ) = 1.103 volts Is the flow of electrons spontaneous? = cell -n cell So, if cell is positive, cell will be negative. Is a reaction spontaneous when G° is negative?
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26.2 Galvanic Cell is an electrochemical cell in which a ____________________ chemical reaction is used to generate an electric current. Electrolytic Cell uses electrical energy provided by an external circuit to carry out ________________________ reactions. Summary
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This note was uploaded on 11/27/2011 for the course CHEMICAL E 20.410j taught by Professor Rogerd.kamm during the Spring '03 term at MIT.

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lecnotes26 - MIT OpenCourseWare http:/ocw.mit.edu 5.111...

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