Question

1) AgI has a Ksp of 8.3 × 10-17, ZnS has a Ksp of 1.6 × 10-24, PbS has a Ksp of 8.3 × 10-28, and CaSO4 has a Ksp of 9.6 × 10-6.

Which is the most soluble?

a) AgI
b) ZnS
c) PbS
d) CaSO4

2) Given a Ksp for AgBr of 5.0 × 10-13, what happens when 50 ml of 0.002 M AgNO3 and 50 mL of 0.002 M NaBr are mixed?

a) AgBr precipitates.
b) AgBr does not precipitate.
c) NaNO3 precipitates.
d) NaNO3 does not precipitate.

Answer 1

For the first question, I think the correct answer would be D. Calcium sulfate would be the most soluble salt in the given choices. The solubility product constant or Ksp expresses the equilibrium of the a solid and the ions it dissociates when in solution. Such that a higher value of Ksp would mean the compound is more soluble in solution. For the second question, the answer would be the first option. Given the amounts of the reactants and the Ksp of AgBr, the product silver bromide would precipitate in the product solution. This is because the resulting concentration of this product is way higher than the solubility of the compound.