[peterschmidt3943]

Hello,

I would like to know why a sediment appears when you mix CaCl2- and Na2SO4 solution?

I know that it is because the ion product exceeds the solubility product, but how can I proof it ?


I

[Enthalpy]

Or because the available ions can produce one compound that is poorly soluble? Can you see one?

[peterschmidt3943]

Na2+ and Cl2-?
or
Ca2+ and SO4-?

[Enthalpy]

Solubility can't be decided by general rules. You have to know a few compounds and whether they are easily soluble or not.

In this case, CaSO₄ is badly soluble in water. If an aqueous solution contains both Ca²⁺ and SO₄^2-, they combine to make a solid that precipitates.

Note that it's a property of the salt, not of its constituent ions. And checking the concentrations versus solubilities would give a more accurate answer than my qualitative one.

Please use the indices and exponents available over the text window at Chemicalforums. What you have typed is impossible to understand. I can't rule out that you need to catch up some lessons about valence, ions and so on.