Define equilibrium law advance knowledge

The equilibrium law, also known as the Law of Mass Action, describes the relationship between the concentrations of reactants and products at equilibrium for a reversible reaction. It states that at a constant temperature, the ratio of product concentrations (raised to their stoichiometric coefficients) to reactant concentrations (raised to their stoichiometric coefficients) is constant, known as the equilibrium constant ($K$). This law provides advance knowledge by allowing prediction of the direction a reaction will shift to reach equilibrium and calculation of equilibrium concentrations.