Determining Solubility in Acidic Solutions / Pure Water

[JwdePhysics]

Homework Statement

How many of the following would you NOT expect to be more soluble in acid than in pure water?

FeS, CuCN, AlPO₄, BaCO₃, AgCl

Homework Equations

None necessary

The Attempt at a Solution

So we know that anything with OH- or anything that has the conjugate base of a weak acid will be more soluble in acidic solution than pure water. Since there is nothing with OH-, we don't have to worry about that. Now the strong acids are H₂SO₄, HNO₃, HBR, HI, HCLO₄, and HCL.

1. FeS has the conjugate base of a weak acid, H₂S, therefore it is more soluble in acid than in pure water, therefore it doesn't contribute to the answer
2.CuCN has the conjugate base of a weak acid, HCN, therefore it is more soluble in acid than in pure water, therefore it doesn't contribute to the answer
3.AlPO₄ has the conjugate base of a weak acid, H₃PO₄, therefore it is more soluble in acid than in pure water, therefore it doesn't contribute to the answer
4.BaCO₃ has the conjugate base of a weak acid, HCO₃, therefore it is more soluble in acid than in pure water, therefore it doesn't contribute to the answer
5. AgCl has the conjugate base of a strong acid, HCL, therefore it is NOT more soluble in acid than in pure water, therefore it contributes to the answer

Therefore the answer should be 1.

Is my logic right or wrong?

 

[Borek]

Your logic looks OK, yet the final answer is blatantly wrong and it contradicts everything you wrote earlier. I suppose it is just kind of typo.

 

[mjc123]

I think he means the number is 1 (answering the asked question "how many?"), rather than No.1 (answering the not-asked question "Which?")

 

[Borek]

Ah, could be. Thanks.