Which factor is crucial in determining the cell potential of a reaction?

The concentration of reactants and products is crucial in determining the cell potential of a reaction due to its direct influence on the Gibbs free energy change and the Nernst equation. According to the Nernst equation, the cell potential (E) is related to the standard electrode potential (E°) and the concentrations of the reactants and products involved in the electrochemical reaction.

As the concentrations of reactants or products change, the cell potential shifts accordingly, reflecting the tendency for the reaction to occur in either direction. This relationship is fundamental in electrochemistry because it allows us to predict how changing the concentrations can drive the reaction towards more favorable conditions for producing or consuming species.

In practical terms, if the concentration of a reactant is increased, the cell potential will typically increase, favoring the reaction in the forward direction. Conversely, a decrease in product concentration may also influence the potential, illustrating how crucial these concentrations are in maintaining or altering the potential of the electrochemical cell.