In a lab experiment, a concentrated solution of NH3 was added to a solution containing Cu2 ions, converting most of the copper to the Cu(NH3)42 complex ion. We can represent the resulting equilibrium as: Cu(NH3)42 (aq) ↔ Cu2 (aq) 4NH3(aq), Kc = 2.15 x 10-13 At equilibrium for this reaction, [NH3] = 2.50M and the total copper concentration is 0.075M, i.e. [Cu2 ] [Cu(NH3)42 ] = 0.075M. Determine the actual [Cu2 ] (i.e. the concentration of the uncomplexed copper ion) at equilibrium in this solution. Hint: note that Kc is very small!