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Unformatted text preview: tion. In many instances, the electrode is actually one of the chemical components of the half-reaction. For example, the copper electrode is involved directly in the half reaction, Cu2+ + 2e- Cu. In other cases, however, the electrode does not participate in the chemistry of the half-reaction, but merely provides an inert conducting surface on which the electron exchange occurs. For example, when the half reaction Fe3+ + e- Fe2+ is studied, a Pt or C electrode rather than an iron electrode is used. This is because on an iron wire, both Fe3+ + 3 e- Fe(s) and Fe2+ + 2 e- Fe(s) could occur, rather than the Fe3+ / Fe2+ reaction that is of interest. The two electrode compartment must be separated by a barrier that permits ions to migrate inside the cell, but does not allow the contents of the chambers to mix. A glass tube that is filled with a gel saturated with a strong electrolyte such as KNO3 is often used. In this case, the K+ and NO3- ions create a "salt bridge" for the electroche...
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This note was uploaded on 04/09/2013 for the course CHE CHE 2C taught by Professor Nasiri during the Spring '07 term at UC Davis.

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