For a reaction 2 A 2 B+C 2.0 moles of A was placed in a one litre flask and the concentration of B at equilibrium was found to be 0.4 ~mol ~L ⁻¹ . The equilibrium constant at 30^ C is 10⁻⁴

Step-by-step solution

The reaction is 2A 2B + C . Initial moles: [A]₀ = 2.0 mol L ⁻¹ , [B]₀ = 0 , [C]₀ = 0 . At equilibrium, let the concentration of B be 0.4 mol L ⁻¹ . From the stoichiometry of the reaction, if 2x moles of B are formed, then x moles of C are formed and 2x moles of A are consumed. Given [B]_ eq = 2x = 0.4 , so x = 0.2 mol L ⁻¹ . Equilibrium concentrations are: [A]_ eq = 2.0 - 2x = 2.0 - 0.4 = 1.6 mol L ⁻¹ [B]_ eq = 0.4 mol L ⁻¹ [C]_ eq = x = 0.2 mol L ⁻¹ The equilibrium constant K_c is given by: K_c = [B]^2 [C] [A]^2 K