What is the term for the state in which the forward and reverse rates are equal in a reversible reaction?

• A. Equilibrium state
• B. Dynamic equilibrium
• C. Steady state
• D. Kinetic control

Answer: (B)

In a reversible reaction, both directions occur at the same time. When the forward rate equals the reverse rate, the overall concentrations stop changing with time, yet the molecules keep interconverting. This situation is called dynamic equilibrium because there is ongoing microscopic activity even though the macroscopic properties are constant.

The term dynamic emphasizes that the process is still dynamic at the molecular level, not a static halt. Calling it simply an equilibrium state is less precise, and steady state usually applies to open systems with a continuous flow that keeps concentrations constant in a different way. Kinetic control refers to which products form faster, not to the condition where forward and reverse rates balance.