What occurs when the rates of the forward and backward reactions are equal?

When the rates of the forward and backward reactions are equal, the system reaches a state known as dynamic equilibrium. At this point, the concentrations of both the reactants and products remain constant over time, although the reactions continue to occur in both directions. This means that while individual molecules are constantly reacting to form products and reactants, the overall concentrations do not change because these two processes are occurring at the same rate.

In this state, there is no net change in concentration, resulting from the balance of the forward reaction (where reactants convert to products) and the reverse reaction (where products convert back to reactants). Thus, the correct choice provides an accurate description of what happens when reactions achieve equilibrium, highlighting the constant nature of the concentrations of both reactants and products without implying that the reaction stops or that the concentration of one or the other continues to change.