Gold Standard Exam 3 Question: Molar Solubility

[Necr0sis713]

So there's a question on their FL 3:

Ca(OH)2 has approximately the same Ksp as CaSO4. Which of them has the greater solubility in terms of mol L-1?

The answer ended up being Ca(OH)2. I don't get why CaSO4 doesn't have a higher molar solubility though.

Wouldn't the molar solubility of CaSO4 simply be the square root of Ksp, while for Ca(OH)2 it's the cubed root of 1/4?

So wouldn't CaSO4 "have the higher number" per say, so it has a higher molar solubility?

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[salemstein]

Wouldn't the molar solubility of CaSO4 simply be the square root of Ksp, while for Ca(OH)2 it's the cubed root of 1/4?

So wouldn't CaSO4 "have the higher number" per say, so it has a higher molar solubility?

Careful with your math there. Say Ksp = 10^-9. Square rt of that is 3*10^-5, while cube rt is 1*10^-3. The Cube rt is bigger than square root.

 

[Necr0sis713]

I had a feeling that this would be the case. lol.