What is the term for the state where the rate of the forward reaction equals the rate of the reverse reaction?

• A. Activation energy
• B. Catalyst
• C. Chemical Equilibrium
• D. Rate law

Answer: (C)

The main idea is recognizing what happens in a reversible reaction when the opposing directions balance each other. When the forward rate (reactants turning into products) equals the reverse rate (products turning back into reactants), the system has reached chemical equilibrium. At this point, the concentrations of reactants and products remain constant over time, even though molecules keep exchanging in both directions. Temperature governs the exact balance, and the equilibrium constant describes the ratio of product to reactant concentrations at that temperature, indicating which side is favored.

Think of what each other term means to see why they don’t describe the same state: activation energy is the energy barrier that must be overcome for a reaction to start, and a catalyst lowers this barrier and speeds up both directions without changing the final balance of reactants and products. The rate law, on the other hand, tells you how fast the reaction proceeds given the concentrations—it's about speed, not the condition where the forward and reverse rates are equal.