Equilibrium Defined by Equal Reaction Rates

Steps:

• Recall that chemical equilibrium occurs when forward and reverse reaction rates balance, maintaining constant concentrations.
• Evaluate A: Equal concentrations imply 1:1 stoichiometry, not true for all reactions.
• Evaluate B: Constant concentrations result from equilibrium but do not define it.
• Evaluate C: Matches the core definition of equilibrium.

Why C is correct:

• By definition, dynamic equilibrium requires the forward rate to equal the reverse rate, as per the law of mass action.

Why the others are wrong:

• A: Concentrations depend on equilibrium constant K, not equality.
• B: Describes a consequence, not the defining condition.
• D: Incomplete option provides no valid statement.

Final answer: C