What role does Gibbs free energy play in electrochemistry?

Gibbs free energy is a fundamental thermodynamic quantity that helps determine whether a chemical reaction can occur spontaneously under constant temperature and pressure conditions. In the context of electrochemistry, Gibbs free energy (ΔG) is directly related to the electromotive force (E) of a galvanic cell through the equation ΔG = -nFE, where n is the number of moles of electrons transferred and F is Faraday's constant.

When ΔG is negative, the reaction is spontaneous, meaning it can proceed without any external energy input. This is critical for electrochemical reactions, as spontaneous reactions generate electrical energy, making them the basis for batteries and electrochemical cells. Conversely, if ΔG is positive, the reaction is non-spontaneous and requires energy input to occur.

Thus, the correct choice highlights the essential role of Gibbs free energy in predicting the feasibility of electrochemical reactions, providing insights into which reactions will proceed and how they can be harnessed for energy conversion.