Lesson_23 - Lesson 23 How half-cell potentials are measured...

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Lesson 23 Standard cell potentials The voltage of galvanic cells depends on: Reactants used in the two half-cells Concentrations in the two half-cells Temperature In order to compare the voltages of different galvanic cells, it is necessary to define a standard state : 1.0 M concentration for dissolved species 1 atm pressure for gases
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Lesson 23 Sign convention for E o cell
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Lesson 23 Potentials for half-cell reactions Galvanic cells can be constructed from a very large number of different combinations of two half-cells. Is it necessary to measure the standard cell potentials for all these possible combinations? This can be avoided by defining half-cell potentials : Half-cell potentials are assigned to a half-cell only. When two half-cells are combined to form a galvanic cell, the standard cell potential of the resulting galvanic cell can be calculated from the knowledge of the two half-cell potentials.
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Unformatted text preview: Lesson 23 How half-cell potentials are measured Lesson 23 Measuring E o Cu2+/Cu and E o Zn2+/Zn Lesson 23 • Positive potentials measure the tendency of the reduction reaction taking place when a half-cell is combined with the hydrogen half-cell: +-2 H+/H2 Lesson 23 Lesson 23 A Cu ( s ) strip is immersed in a AgNO 3 solution and in a Zn(NO 3 ) 2 solution. Which flask contains the AgNO3 solution? Lesson 23 Example 1 In a galvanic cell, one half-cell consists of a zinc strip Lesson 23 Example 2 Lesson 23 Example 3 Bromine is sometimes used in place of chlorine as a disinfectant in swimming pools. If the effectiveness of a chemical as a disinfectant depends solely on its strength as an oxidizing agent, do you expect bromine to be better or worse than chlorine as a disinfectant, at a given concentration? Lesson 23 Suggested readings 20.2 Standard Electrode Potentials...
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This note was uploaded on 04/13/2009 for the course CHEMISTRY 102 taught by Professor Soares during the Spring '09 term at Waterloo.

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Lesson_23 - Lesson 23 How half-cell potentials are measured...

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