Using the information below, which answer lists the salts in order of increasing solubility?

PbSO4 Ksp = 1.6 x 10^-8
PbS Ksp = 8 x 10^-28
PbI2 Ksp = 7.1 x 10^-9
PbCl2 Ksp = 1.6 x 10^-5

a. PbS < PbI2 < PbSO4 < PbCl2

b. PbI2 < PbCl2 < PbS < PbSO4

c. PbCl2 < PbI2 < PbSO4 < PbS

I believe the answer is B.

1 answer

I don't agree. If you are solving this problem by comparing the Ksp values, that's the wrong way to do it. You must actually calculate the solubility BECAUSE
a and b are sqrt Ksp while c and d are (Ksp/4)^1/3. Without going through any of the calculations I suspect b is correct because surely PbS is the smallest and a is the only answer that begins with PbS. I could be wrong but you should confirm that by actually calculating each then you can arrange them from low to high.