If the of a reaction is less than zero, the reaction will in fact be exergonic. These reactions will be favorable and spontaneous, and energy is released in these reactions. Thus, endergonic is incorrect.

Exothermic reactions release heat (think exothermic = explosion = creates heat), and this is due to the release of energy from the reactant bonds. These reactions have less than zero. Endothermic reactions are just the opposite and actually require energy to occur, and therefore do not occur spontaneously nor release heat.

The temperature and pressure of the reactants and products of any given reaction will determine the value of . However, this is entirely dependent of the reaction rate, which is determined by how the concentrations of the reactants and products change over the course of the reaction. Additionally, every reaction is unique, so "one-half" or any other exact metric cannot be applied as the definition.

In equilibrium, both the forward and reverse reactions continue to occur, but they do so in a way that is equal and thus, there is no net change of reactants and products in the system. is zero in this case because net changes to the system have ceased, and thus the free energy is no longer in flux.