Consider a galvanic cell at standard conditions based on the following half reactions:

Au³⁺ + 3e^- → Au ϐ^o = 1.50 V

Fe³⁺ + e^- → Fe²⁺ ϐ^o = 0.77 V

When enough NaCl(s) is added to the compartment containing gold to make the [Cl₂] = 0.10 M, the cell potential is observed to be 0.31 V. Assume that Au³⁺ is reduced, and assume that the reaction in the compartment containing gold is Au³⁺(aq) + 4Cl₂(aq) ⇌ AuCl₄^–(aq) Calculate the value of K for this reaction at 25^oC.