Quant_Lect_EchemI - quinone/hydroquinone, E = 0.700 V, E '...

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Introduction to Electrochemistry I. Since chemistry is what happens when we make and break bonds and since bonds are made of electrons and since electrochemistry deals with additions of or removal of electrons from molecules thus almost all chemistry is electrochemistry! II. The basic rules: 1. Potential is the energy with which electrons may be moved. 2. Current is the rate of electrochemical reaction. 3. For electrochemical reaction to occur, the electron donor and acceptor must be within a few Angstroms of each other, effectively in contact. 4. One can control current or potential, but not both. 5. If current is non-zero, systems are typically heterogeneous, so that transport as well as reaction rate at interfaces influences the relationship between current and potential. III. At zero current, potential is related to activity through the Nernst equation. IV. E 0 vs. E 0 '. E 0 : standard potential. E 0 ': Formal potential (E 0 shifted by influence of pH, ionic strength, and matrix complexation. If pH not specified, presume pH=7). For
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Unformatted text preview: quinone/hydroquinone, E = 0.700 V, E ' = 0.286 V. V. Potential of the saturated calomel electrode is +0.241 V. What is potential of a solution Page 1 of 2 Untitled Document 12/8/2010 https://courses.las.illinois.edu/file.php/173/Quant_Lect_EchemI.html containing 0.1 M Cu 2+ and 0.01 M Cu + , given E for Cu 2+ + e Cu + is 0.161 V? VI. Addition of energies to combine half-reactions. G = -RT ln K = - nFE . Demonstration: Cu 2+ + e Cu + is 0.161. Cu + + e Cu is 0.518 V. So what is E for Cu 2+ + 2e Cu? (Answer: 0.339 V). VII. In principle, potentiometry looks at activity, not concentration. Non-ideality: liquid junction potential. VIII. F = charge (in Coulombs) per mole = 96485.33. At 25C, ln(10) RT/F = ln(10)*8.31447 J/mol K * 298.15 K/96485.33 Coul/mol = 0.05916 J/Coul = 59.16 mV. Page 2 of 2 Untitled Document 12/8/2010 https://courses.las.illinois.edu/file.php/173/Quant_Lect_EchemI.html...
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This note was uploaded on 04/02/2012 for the course CHEMISTRY 222 taught by Professor Mcdonald during the Fall '11 term at University of Illinois, Urbana Champaign.

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Quant_Lect_EchemI - quinone/hydroquinone, E = 0.700 V, E '...

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