Significance of the half-cell potential

This is the solubility product constant of copper hydroxide. 

In the case of the metal ion/metal electrode, the half-cell potential is a measure of the tendency of the reaction + hq to occur. It is thus a measure of the tendency of 

Thus the standard electrode potential is a measure of the standard molar Gibbs energy of the metal ion relative to the hydrogen ion. 

Active metals such as Zn, Na, or Mg have highly negative standard potentials. Their compounds are not reduced by hydrogen, but rather the metal itself can be oxidized by to yield H2. Noble metals such as Cu and Ag have positive (/ ° s. Compounds of these metals are readily reduced by H2 the metals themselves are not oxidized by hydrogen ion. 

Since the potential of a metal depends on the activity of the metal ion in solution, factors that influence the activity of the ion will ipso facto influence the electrode potential. For silver, the Nernst equation is 

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