What is one effect of adding product to a system at equilibrium?

When product is added to a system at equilibrium, the principle of Le Chatelier indicates that the system will respond by shifting to counteract the change, in this case, by reducing the concentration of the added product. This results in the equilibrium shifting to the left, or toward the reactants.

In a chemical equilibrium, both the forward and reverse reactions occur at the same rate, and when a change is made—like the addition of product—the system attempts to restore equilibrium. By shifting to the left, more reactants are produced, helping to lower the concentration of the product that was just added.

The incorrect options relate to the concepts of equilibrium shifts: shifting to the right would mean favoring the formation of more products, which is not the case when additional product is introduced. Saying the equilibrium position remains unchanged overlooks the dynamic nature of equilibrium, which always strives to adjust to any changes in concentration. The assertion that the reaction speed increases dramatically is misleading; while the rates of both the forward and reverse reactions could initially be affected, the equilibrium will still shift in response to maintain a new balance.