What makes some chemical reactions at the electrodes irreversible?

The nature of some chemical reactions at the electrodes being irreversible is primarily due to the depletion of reactants over time. In many electrochemical processes, particularly those involving batteries or galvanic cells, a finite quantity of reactants is available for the reaction. Once these reactants are consumed, the reaction cannot spontaneously reverse itself because the reactants have been reduced to a point where they are no longer present in sufficient amounts to support the forward reaction.

In contrast, other factors like the inability to produce heat, an excess of products, or the stability of the electrolyte do not directly determine whether a reaction is reversible. While temperature changes might affect reaction rates, they do not dictate the directionality of the chemical process. Similarly, having an excess of products may not prevent a reaction from reversing; in fact, it can sometimes encourage the reverse reaction to occur under the right conditions. The stability of the electrolyte is important for maintaining reactions but does not inherently make reactions irreversible. Thus, it is the consumption of reactants that solidifies the irreversibility in many electrochemical reactions.