Electrochemical Reference Level for Hydrated Ions

In electrochemistry, the chemical potential of hydrated ions has been determined from the equilibrium potential of ion transfer reactions referred to the normal hydrogen electrode. For the reaction of metal ion transfer (metal dissolution-deposition reaction) of Eqns. 6-16 and 6-17, the standard equilibriiun potential Sive in terms of the standard chemical potential, li, by Eqn. 

It follows from Eqn. 6-22 that the standard chemical potential of hydrated ions determined from the standard equilibrium potential of the ion transfer reaction is a relative value that is to the standard chemical potential of hydrated protons at unit activity, which, by convention in aqueous electrochemistry, is assigned a value of zero on the electrodiemical scale of ion levels. 

The reaction equiUbrivun of the normal hydrogen electrode, H2.g = 2 H , + 2eHVH, where eH 2 equilibrium redox electron, can be obtained by the 

If we set at a value of zero according to the conventional chemical thermodynamic energy scale, the standard chemical potential of a hydrated proton,, is given by Eqn. 6-24  

---