In general, an individual reaction expressed as R1 + R2 → R3 + R4 approaches equilibrium with the progress of reaction according to a rate equation such as equation (1), because it leads to decreases in the concentrations of reactants, 𝐶 1 and 𝐶 2 , and hence to a decrease in the reaction affinity 𝐴 which is given in an approximation of using the concentration instead of the activity as