Question

"The osmotic pressure of a saturated solution of strontium sulfate at 25C is 21 torr. What is the solubility product of this salt at 25C (Hint: calculate molarity from the colligative properties eqn of osmotic pressure and use it in the equilibrium expression"
I converted torr to atm and solved P=MRT for molarity (M) = 0.00113M
but I'm not sure what to do next...if you can tell me how to do this problem that would be much appreciated!!!

Thank you

Answer 1

I think you omitted the van't Hoff factor for SrSO4. There are two particles so
P = iMRT which makes the molarity just 1/2 of your number = ??
Since that is the solubility of SrSO4, then
SrSO4(s) ==> Sr^+ + SO4^-2
Ksp = (Sr^+)(SO4^-2)
Sr^+2 = ??
SO4^-2 = ??
The internet gave me a Ksp 3.44 x 10^-7 which makes this fairly close.