The disorder due to state is accounted for in the quantity . Since the Gibbs free energy is negatively related to the total entropy change, reactions that proceed in the direction of increasing entropy proceed in the direction of decreasing free energy (proceed such that less of the system is ordered). Negative also favors a lower .
When free energy is plotted as a function of proportion of products present in the system, a curve on a Cartesian graph is obtained. The equilibrium of the reaction occurs at the minimum of the curve (at which point the slope is horizontal).
It is also important to note that <0 for a spontaneous reaction, >0 for a non spontaneous reaction and =O at equilibrium.
Under standard conditions, the standard reaction free energy is obtained:
