What is the implication of a positive Gibbs free energy (G) value?

A positive Gibbs free energy value indicates that the reaction is non-spontaneous under the given conditions. Gibbs free energy (G) is a thermodynamic quantity that combines enthalpy and entropy to predict whether a reaction will occur without external input. When the value of G is positive, it suggests that the system requires a net input of energy for the reaction to proceed, meaning the reaction will not happen spontaneously.

In contrast, a negative Gibbs free energy indicates a spontaneous reaction, where the process can occur without any additional energy input. An equilibrium state is characterized by a Gibbs free energy value of zero, indicating that the forward and reverse reactions occur at the same rate. Additionally, the concept of being reactant-favored or product-favored involves the relative stability of reactants and products, which can also be inferred from a Gibbs free energy analysis; however, a positive G specifically denotes non-spontaneity rather than a specific favorability. Thus, the interpretation of a positive Gibbs value is explicitly linked to its implication of non-spontaneity in thermodynamic processes.