(a) AgCl(s) ==> Ag+(aq) + Cl-(aq)
ΔG°rxn = sum (ΔG°f products) - sum (ΔG°f reactants) = ((1 mole Ag+(aq))(77.1 kJ/mole) + (1 mole Cl-(aq))(-131.2 kJ/mole)) - (1 mole AgCl(s)(-109.8 kJ/mole) = +55.7 kJ/mole
(b) The solubulity product constant is Ksp for the reaction in (a).
ΔG° = -RTlnK, or, K = e^(-ΔG°/RT) = e^(-55,700 J)/(8.31 J/mole K)(298 K) = e^-22.5 = 1.7 x 10^-10
(c) and (d) are done just like (a) and (b). You should get values of
ΔG°rxn = +70.0 kJ
Ksp AgBr = 5.3 x 10^-13