What type of equilibrium is established in a reversible reaction?

In a reversible reaction, a dynamic equilibrium is established, where the rates of the forward and reverse reactions are equal. This means that reactants are continuously being converted into products and products are being converted back into reactants at the same rate. As a result, the concentrations of both reactants and products remain constant over time, although the molecules are still actively reacting within the system.

This contrasts with a static equilibrium, which implies that no movement or reaction occurs, leading to a completely unchanging state. Therefore, a static equilibrium does not apply to reversible reactions, where continual processes are taking place.

Non-chemical equilibrium is not a term typically associated with chemical reactions, making it an unsuitable choice for this context. Similarly, a phase equilibrium pertains specifically to the balance between different physical states of a substance (such as solid, liquid, or gas), rather than the chemical changes occurring in a reversible reaction. Thus, the choice of dynamic equilibrium is the only appropriate response, reflecting the ongoing nature of reversible reactions.