An aqueous solution of volume 500 ml, when the reaction: 2Ag⁺(aq) + Cu(s) ⇌ Cu²⁺(aq) + 2Ag(s), reached equilibrium, the concentration of Cu²⁺ ions was x M. To this solution, 500 ml of water is added.

Question

An aqueous solution of volume 500 ml, when the reaction: 2Ag⁺(aq) + Cu(s) ⇌ Cu²⁺(aq) + 2Ag(s), reached equilibrium, the concentration of Cu²⁺ ions was x M. To this solution, 500 ml of water is added. At the new equilibrium, the concentration of Cu²⁺ ions would be

Prashant Kotian · Accepted Answer

Correct answer: D. Adding 500 ml of water doubles the volume, initially halving all concentrations: [Cu²⁺] = x/2 = 0.5x, and [Ag⁺] becomes half. Qc = [Cu²⁺] / [Ag⁺]² = (0.5x) / ([Ag⁺]_initial / 2)² = 2 × Kc. Since Qc > Kc, the reaction shifts backward to reach equilibrium, further decreasing the concentration of Cu²⁺ below 0.5x M. Therefore, correct answer is D.

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