Determinng molar solubility based on the pH of a solution.?

Question

How can you determine if the molar solubility of a solution will be affected by the pH?
for examplewhich will not be affected by pH
a.Na2Co3 b.NaF c. FePO4 d. KClO4 e.NiS. I dont necessarily need an answer I just want to know how to determine this. thanks

Answer 1

If the anion is appreciably hydrolysed in solution, then the molar solubility will be affecte by a change in pH. This will be true for all salts of weak acids, but not those of strong acids.

For example, in NiS, S2- + H2O <-----> (H3O)+ + HS-

If you lower the pH, this equilibrium will go to the left, increasing [S2-] and making it more likely that Ksp will be exceeded.

Answer 2

Ksp = product of the ions. From pH the H+ ions = 1.2x10^3 = C6HJ5COO- ions Ksp =, (1.2x10^-3)^2 = 1.44x10^-6 Moles per Litre. P.S. Soilids don't have a concentration, so we can ignore it here. But it is immportant ffor calculating Ka and Kb.