Skill 11.5 Relating cell potentials to spontaneity and equilibrium constants

Skill 11.5 Relating cell potentials to spontaneity and equilibrium constants 

See Skill 11.3 for information on cell potentials. The standard potential of an oxidation half-reaction E is equal in magnitude but has the opposite sign to the potential of the reverse reduction reaction. Standard half-cell potentials are tabulated as reduction potentials. These are sometimes referred to as standard electrode potentials E°. Therefore, 

When the value of E° is positive, the reaction is spontaneous. If the E° value is negative, an outside energy source is necessary for the reaction to occur. In the above example, the E° is a positive 1.10 V. therefore this reaction is spontaneous. 

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