All rate laws for reversible reactions must reduce to the thermodynamic relationship relating the reacting species concentrations at equilibrium. At equilibrium, the rate of reaction is identically zero for all species (i.e., –rA ≡ 0). That is, for the general reaction
the concentrations at equilibrium are related by the thermodynamic relationship for the equilibrium constant KC (see Appendix C).
Thermodynamic Equilibrium Relationship
The units of the thermodynamic equilibrium constant, KC, are (mol/dm3)d + ...