For electrode reversibility to be maintained, all the reactants and products involved in the half-reaction must be present at the electrode. There are several types of reversible electrodes (half-cells).In metal-metal-ion electrodes, a metal balances electrochemically with a solution of its own ions. Examples are Cu2+|Cu and Zn2+|Zn. Metals that react with the solvent, like group 1 and most group 2 metals, which react with water, and zinc, which reacts with aqueous acidic solutions, cannot be...