The change in concentration of reactants and products in a reversible chemical reaction at equilibrium can be understood 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 re-establish a new equilibrium.When the concentration of reactants or products in a reversible reaction is changed, the equilibrium will shift to either favor the forward or reverse reaction in order to re-establish equilibrium. Here's how the change in concentration affects the rate of the reaction:1. Increase in reactant concentration: If the concentration of a reactant is increased, the system will shift towards the products to counteract the change. This means the forward reaction rate will increase, and the reverse reaction rate will decrease until a new equilibrium is established.2. Decrease in reactant concentration: If the concentration of a reactant is decreased, the system will shift towards the reactants to counteract the change. This means the forward reaction rate will decrease, and the reverse reaction rate will increase until a new equilibrium is established.3. Increase in product concentration: If the concentration of a product is increased, the system will shift towards the reactants to counteract the change. This means the forward reaction rate will decrease, and the reverse reaction rate will increase until a new equilibrium is established.4. Decrease in product concentration: If the concentration of a product is decreased, the system will shift towards the products to counteract the change. This means the forward reaction rate will increase, and the reverse reaction rate will decrease until a new equilibrium is established.In summary, the change in concentration of reactants and products affects the rate of a reversible chemical reaction at equilibrium by shifting the reaction towards either the reactants or products to re-establish a new equilibrium. This results in changes to the forward and reverse reaction rates until the new equilibrium is reached.