The equilibrium constant expression for a reaction aV + bX ⇌ cY + dZ can be derived from chemical kinetics by treating reaction rates as probabilities of molecular collisions: the forward and reverse rate laws are each proportional to the product of reactant concentrations raised to their stoichiometric coefficients, since concentration approximates the likelihood of finding the required number of molecules within a given volume. At equilibrium, the forward and reverse rates are equal (not the concentrations), and equating the two rate expressions and isolating the ratio of their rate constants yields the equilibrium constant K = ([Y]^c[Z]^d)/([V]^a[X]^b). This connects the domain of chemical kinetics (rate laws, rate constants, collision/probability theory) to chemical equilibrium theory, showing the equilibrium constant expression as a consequence of dynamic balance between opposing reaction rates rather than an arbitrary formula.
The equilibrium constant expression for a reaction aV + bX ⇌ cY + dZ can be derived from chemical kinetics by treating reaction rates as probabilities of molecular collisions: the forward and reverse…