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Electrode Reactions That Deviate From Complete Equilibrium

The example that was discussed earlier, the reaction of lithium with iodine to form LiI, dealt with elements and thermodynamically stable phases. By knowing a simple parameter, the Gibbs free energy of formation of the reaction product, the cell voltage under equilibrium and near-equilibrium conditions can be calculated for this reaction. If the cell operates under a fixed pressure of iodine at the positive electrode and at a stable temperature, the Gibbs phase rule indicates that the number of the residual degrees of freedom F in both the negative and the positive electrodes is zero. Thus the voltage is independent of the extent of the cell reaction in both cases. This is a case in which the reaction involves species that are absolutely stable. The description of a phase as absolutely stable means that it is in the thermodynamic state, e.g., crystal structure, with the lowest possible value of the Gibbs free energy for its chemical composition.

This is a case in which the reaction involves species that are absolutely stable. The description of a phase as absolutely stable means that it is in the thermodynamic state, e.g., crystal structure, with the lowest possible value of the Gibbs free energy for its chemical composition.

Keywords

Gibbs Free Energy Electrode Reaction Complete Equilibrium Soft Chemistry Residual Degree 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    J. Livage. Le Monde, October 26, 1977.Google Scholar
  2. 2.
    J. Rouxel, Soft Chemistry Routes to New Materials — Chimie Douce, Materials Science Forum,1994, pp. 152–153.Google Scholar

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© Springer Science+Business Media, LLC 2009

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