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Galvanic Cells​

​Learning Objetives

• Describe and relate the definitions of electrode and cell potentials

• Interpret electrode potentials in terms of relative oxidant and reductant strengths

• Calculate cell potentials and predict redox spontaneity using standard electrode potentials

​The electrode potential

​In electrochemistry, the electrode potential is the electromotive force of a galvanic cell built from a standard reference electrode and another electrode to be characterized.

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By convention, the reference electrode is the standard hydrogen electrode (SHE). It is defined to have a potential of zero volts.

​​The SHE electrode

​The SHE electrode can be connected to any other electrode by a salt bridge to form a cell.

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If the second electrode is also at standard conditions, then the measured cell potential is called the standard electrode potential for the electrode.

The standard electrode potential for the SHE is zero, by definition.

​Standard electrode potentials

​Standard electrode potentials reflect the relative oxidizing strength of the half-reaction reactant, with stronger oxidants exhibiting larger (more positive) E°_X values. Tabulations of standard electrode potentials may be used to compute standard cell potentials, E°_cell, for many redox reactions.