Find Ksp value for bismuth sulfide?

Question

Calculate the Ksp value for bismuth sulfide, Bi2S3, which has a molar solubility of 1.0*10da-15mol/L @ 15C

Answer 1

OK...When bismuth sulfide dissolves, it will produce 2 Bi3+ ions and 3 S2- ions. So, the formula for the Ksp is:

Ksp=[Bi3+]^2[S2-]^3

The molar solubility of 1 X 10^-15 mol/L says that in a saturated solution that many moles of the original compound dissolves in a liter. So, the concentration of Bi3+ ions will be 2 X 10^-15 M, and the sulfide ion concentration will be 3 X 10^-15 M.

Substitute those values in the Ksp equation and solve for your answer.

Answer 2

Bismuth Sulfide