[hlp805]

Why do MCO₃ precipitates dissolve in acid much better than MSO₄ precipitates (where M represents Mg²⁺, Ba²⁺, Sr²⁺, and Ca²⁺)?

[Borek]

Think about the acid strength. The same applies to your other question.

[hlp805]

I don't know much about acid strength...do you know of a free website where I can learn about it?

[Borek]

http://www.chembuddy.com/?left=pH-calculation&right=toc

But this is probably much mor thany you need.

Think: if the acid is weak, it doesn't dissociate fully. What will happen in the presence of other, much stronger acid?

[BluRay]

Why do MCO₃ precipitates dissolve in acid much better than MSO₄ precipitates (where M represents Mg²⁺, Ba²⁺, Sr²⁺, and Ca²⁺)?

In the spirit of the advices you had, consider the two following reactions:

CO₃^2- + 2H⁺ <--> H₂CO₃
SO₄^2- + 2H⁺ <--> H₂SO₄

which one do you think it has the greater equilibrium constant?