2. A sample containing 0.0500 mol of Fe2(SO4)3 is dissolved in enough water to make 1.00 L of solution. This solution contains hydrated SO42- and Fe(H2O)63+ ions. The latter behaves as an acid according to the equation:
Fe(H2O)63+ (aq) ↔ Fe(H2O)5OH2+ (aq) + H+ (aq)
a. Calculate the expected osmotic pressure of this solution at 25° C if this acid dissociation is negligible.
b. The actual osmotic pressure is of the solution is 6.80 atm at 25° C. Calculate the Ka for the acid dissociation reaction of Fe(H2O)63+, assuming no ions cross the semipermeable membrane.