The law of chemical equilibrium is a fundamental principle in chemical reactions that governs the distribution of reactants and products at equilibrium conditions. Some synonyms for the law of chemical equilibrium are the law of mass action, equilibrium constant principle, and the principle of microscopic reversibility. The law of mass action applies to chemical systems at equilibrium and states that the rate of a chemical reaction is proportional to the concentration of the reactants and products raised to the power of their stoichiometric coefficients. The equilibrium constant principle refers to the relationship between the concentrations of reactants and products at equilibrium, while the principle of microscopic reversibility states that the forward and backward reactions occur simultaneously and obey the same laws of chemical kinetics.