Gibbs Free Energy?

Question

In acidic soils, dissolved Al^3+ undergoes a complex formation reaction with SO4^2- to form [AlSO4^1+]. The equilibrium constant at 25 deg C for the reaction is 1585. Calculate the GIbbs free energy change for this reaction. Would it be better to use the fluoride ion to trap aluminum form the soil if the equilibrium constant for the formation equilibrium constant of the complex [AIF^2+] is 10^7.

Answer 1

∆G° = -RTlnK

∆G° = - (8.3144 J/K-mol) (25 + 273 K) ln(1585)

∆G° = -18.26 kJ/mol

For F-, ∆G° = -39.94 kJ/mol.

If the F- doesn't react with other ions in the soil, yes, this would be better.

Answer 2

Actually

∆G° = -RTlnK

∆G° = - (8.3144 J/K-mol) (25 + 273 K) ln(1585)

∆G° = -18.26 kJ/mol

For F-, ∆G° = -39.94 kJ/mol.