(a) Using the ion-pair equilibrium constant from Appendix J, with activity coefficients = 1, find the concentrations of species in 0.025 M MgSO₄. Hydrolysis of the cation and anion near neutral pH is negligible. Only consider ion-pair formation. You can solve this problem exactly with a quadratic equation. Alternatively, if you use Solver, set Precision to 1e-6 (not 1e-16) in the Solver Options. If Precision is much smaller, Solver does not find a satisfactory solution. The success of Solver in this problem depends on how close your initial guess is to the correct answer.

(b) Compute a new ionic strength and repeat part (a) with new activity coefficients from the Davies equation. Perform several iterations until the ionic strength is constant. The fraction of ion pairing that you find should be close to that in Box 7-1, which was derived with Debye Hückel activity coefficients.

(c) We naively assigned the ionic strength of 0.025 M MgSO₄ to be 0.10 M. What is the actual ionic strength of this solution?