What does a decrease in Gibbs free energy indicate about a reaction?

A decrease in Gibbs free energy signifies that a reaction is moving towards a state of greater stability and that it has the potential to occur spontaneously. Gibbs free energy is a thermodynamic quantity that combines enthalpy and entropy to determine the favorability of a reaction at constant temperature and pressure.

When the Gibbs free energy decreases (i.e., ΔG < 0), it indicates that the products of the reaction are thermodynamically more stable compared to the reactants. This stability leads to a natural tendency for the reaction to proceed without the need for continuous input of external energy; hence, it is classified as a spontaneous reaction.

In contrast, if Gibbs free energy were to increase, it would suggest that the reaction is non-spontaneous and would not occur under the current conditions. Additionally, if the Gibbs free energy change is zero, that would imply the system is at equilibrium, meaning that the forward and reverse reactions occur at the same rate, and no net change in concentration of reactants and products is observed.

Understanding these principles is critical in predicting how chemical reactions will behave under varying conditions.