Which statement about Kc is true?

• A. Kc > 1 means products are favored at equilibrium.
• B. Kc > 1 means reactants are favored at equilibrium.
• C. When Kc is large, products are favored at equilibrium.
• D. Kc equals the reciprocal of the equilibrium constant.

Answer: (C)

Kc tells us where the equilibrium lies by comparing product and reactant concentrations. It’s the ratio of product concentrations (raised to their stoichiometric powers) to reactant concentrations. If this ratio is large, the system sits far toward the product side, so products are favored at equilibrium. Saying Kc is large conveys just how strongly the reaction favors products, which is more informative than simply saying Kc is greater than 1. For the other idea, the reverse statement isn’t generally true: the reciprocal relationship applies to the reverse reaction (its Kc is 1 divided by the forward Kc), not that a single Kc equals its own reciprocal. So the best description is that a large Kc means the equilibrium favors the formation of products.