If the concentration of I^-1 is found to be 2.4x10^-3 mol/L in a saturated solution of PbI2, what is the Ksp of PbI2?

The given answer is 6.9x10^-9

1 answer

........PbI2 ==> Pb^2+ + 2I^-
I......solid.....0........0
C......solid.....x........2x
E......solid.....x........2x

Ksp = (Pb^2+)(I^-)^2
Ksp = (x)(2x)^2

So the problem tells you the value of 2x. Substitute 2x and x into the Ksp expression and solve for Ksp.