Is a chemical reaction proceeding to equilibrium considered spontaneous or non-spontaneous?

A chemical reaction proceeding to equilibrium is considered spontaneous because it occurs naturally without the need for external energy input. Spontaneity in chemical reactions is determined by the change in Gibbs free energy (ΔG). A reaction is spontaneous when ΔG is negative, indicating that the reaction can proceed in the forward direction toward equilibrium under the given conditions.

At equilibrium, the system has reached a state where the rates of the forward and reverse reactions are equal, and no net change occurs in the concentrations of the reactants and products. However, the path to reach that equilibrium can be characterized as spontaneous if the system is allowed to evolve freely from its initial state.

This concept of spontaneity also applies regardless of whether the reaction releases heat (exothermic) or absorbs heat (endothermic), as long as the overall change in Gibbs free energy remains negative during the course of the reaction. Hence, it is not limited to conditions of heat release or specific phases, making the option of spontaneity the most universally applicable in this context.