The concentration of reactants and products affects the rate of a chemical reaction at equilibrium through Le Chatelier's Principle. This principle states that if a system at equilibrium is subjected to a change in concentration, temperature, or pressure, the system will adjust itself to counteract the change and restore a new equilibrium.When the concentration of reactants or products is changed, the equilibrium will shift to either the left or right to re-establish equilibrium. If the concentration of reactants is increased, the reaction will shift to the right, favoring the formation of more products. Conversely, if the concentration of products is increased, the reaction will shift to the left, favoring the formation of more reactants.It is important to note that the rate of the reaction at equilibrium remains constant, as the forward and reverse reactions occur at the same rate. However, the concentrations of reactants and products may change as the system adjusts to the new equilibrium.In summary, changing the concentration of reactants or products in a chemical reaction at equilibrium will cause the system to shift in a direction that counteracts the change and re-establishes a new equilibrium. The rate of the reaction at equilibrium remains constant, but the concentrations of reactants and products may change as the system adjusts.