Question

(a) The equilibrium constant at 298 K for the reaction Cu(s) + 2Ag⁺ (aq) ⇌ Cu²⁺ (aq) + 2Ag(s) is 2.0 × 10¹⁵ . The concentrations of Cu²⁺ and Ag⁺ ions are 1.8 × 10^-2 mol L^-1 and 3.0 x 10^-19 mol L^-1 respectively. Is this reaction at equilibrium. Explain.

(b) State the law of chemical equilibrium.

Answer 1

Given,

Equilibrium constant K = 2.0 x 10¹⁵

[Cu²⁺] = 1.8 x 10^-2 mol L^-1

[Ag⁺] = 3.0 x 10^-9 mol L^-1

For the reaction

Cu(S) + 2Ag⁺ (aq) ⇌ Cu²⁺ (aq) + 2Ag (s)

Equilibrium constant K = \(\frac{[Cu^{2+}]}{[Ag^+]^2}\)

2 x 10⁵ = \(\frac{1.8\times10^{-2}}{(3.0\times10^{-9})^2}\)

= 2 x 10¹⁵

Hence, the reaction is at equilibrium.

(b) Law of Chemical Equilibrium: According to this law, "at a given temperature, the product of concentrations of the reaction products raised to the respective stoichiometric coefficient in the balanced chemical equation divided by the product of concentrations of the reactants raised to their individual stoichiometric coefficients has a constant value.’’