K_c is 1.67 × 10²⁰ at 25°C for the formation of iron(III) oxalate complex ion:
Fe³⁺(aq) + 3 C₂O₄^2-(aq) ⇌ [Fe(C₂O₄) ₃]^3-(aq) .
If 0.0200 M Fe³⁺ is initially mixed with 1.00 M oxalate ion,what is the concentration of Fe³⁺ ion at equilibrium?

Question

Quizplus · Accepted Answer

The equilibrium constant expression for the reaction is:K_c = [Fe(C₂O₄)₃^3-] / [Fe³⁺][C₂O₄^2-]³At equilibrium, the concentration of Fe³⁺ can be calculated using the equilibrium constant and the initial concentrations of Fe³⁺ and C₂O₄^2-:K_c = [Fe(C₂O₄)₃^3-] / [Fe³⁺][C₂O₄^2-]³1.67 × 10²⁰ = [Fe(C₂O₄)₃^3-] / [Fe³⁺](1.00 M)³[Fe³⁺] = [Fe(C₂O₄)₃^3-] / (1.67 × 10²⁰)(1.00 M)³The concentration of Fe(C₂O₄)₃^3- at equilibrium can be calculated using the initial concentration of Fe³⁺ and the stoichiometry of the reaction:[Fe(C₂O₄)₃^3-] = 0.0200 M - [Fe³⁺]Substituting this expression into the equation for [Fe³⁺], we get:[Fe³⁺] = (0.0200 M - [Fe³⁺]) / (1.67 × 10²⁰)(1.00 M)³[Fe³⁺] = 1.44 × 10^-22 M

Kc Is 1

K_c Is 1