where the reaction quotient  \(\displaystyle Q_r = \frac{[C]^{\gamma_C}[D]^{\gamma_D}}{[A]^{\gamma_A}[B]^{\gamma_B}}\) .  The thermodynamic driving force for equation (\ref{eqn:simple_reaction_scheme}) can also be defined in terms of the molar free energy of the species involved, usually referred to as a chemical potential (\(\mu\)):