What relationship does cell potential have with the spontaneity of a reaction?

A positive cell potential indicates that a reaction is spontaneous under standard conditions. In electrochemistry, the cell potential, often represented as E°, reflects the driving force behind the redox reaction occurring within an electrochemical cell. When the cell potential is positive, it signifies that the Gibbs free energy change (ΔG) for the reaction is negative, which is a condition for spontaneity.

This relationship is derived from the equation ΔG = -nFE°, where ΔG represents the change in Gibbs free energy, n is the number of moles of electrons transferred, F is Faraday's constant, and E° is the standard cell potential. If E° is positive, ΔG becomes negative, indicating that the reaction will proceed spontaneously in the forward direction.

Conversely, if the cell potential were negative, it would correspond to a positive ΔG, indicating that the reaction is non-spontaneous under standard conditions. Thus, a positive cell potential unequivocally aligns with the concept of a spontaneous reaction, making it a key indicator in predicting the behavior of redox reactions in electrochemical systems.