The mass–action ratio, often denoted by
This assumes that the stoichiometric amounts are all unity. If not, then each species must be raised to the power of its corresponding stoichiometric amount. If the product and reactant concentrations are at equilibrium then the mass–action ratio will equal the equilibrium constant. At equilibrium:
The ratio of the mass–action ratio to the equilibrium constant is often called the disequilibrium ratio, denoted by the symbol
At equilibrium