Double decomposition : CaSO4 & MgSO4

[jmarjorie]

Would anyone know what are the ideal widely available and cheap inorganic compounds to double decompose CaSO4 and MgSO4 into their more water soluble counterparts.

Please note that the sulfates of Calcium and Magnesium themselves are insoluble in water. The other inorganic compounds and their Sulfates have to be soluble in water. Any such compounds ?

[aj47]

I don't really understand what you are asking as both magnesium sulphate and copper sulphate are already soluble in water.

[woelen]

Marjorie is talking about calcium sulfate, not copper sulfate.

 

Magnesium sulfate is water soluble, yes it indeed is very water soluble.

 

Double decomposing CaSO4 into a more soluble calcium salt and a more soluble sulfate is VERY hard. I see no practical way to achieve that, because CaSO4 itself is highly insoluble already. With a LOT of patience you MIGHT be able to dissolve CaSO4 in a solution of Na2-EDTA, forming the very strong soluble calcium-EDTA complex and Na2SO4 in solution, but this is a very cumbersome way, and I do not guarantee that it really works. It just comes into my mind.

[YT2095]

how about Potassium Hydroxide?

 

or Lithium Metal?

[raivo]

IIRC calcium sulfate is somewhat soluble in aqueous ammonia but i do not know what chemical changes cause this.

[YT2095]

actualy I`m wondering if the OP meant the Carbonates of these group 2 elements, such as found in limescale.

it just seems odd that MgSO4 is mentioned as being insoluble?

 

in which case ordinary HCl will do it, or Phosphoric acid.

[John Cuthber]

IRIC CaSO4 is slightly soluble and CaCO3 is rather less so. It might be possible to convert CaSO4 into CaCO3 by boiling it with excess Na2CO3 (this trick works with PbSO4).

That would give Na2SO4 (very impure because of the Na2CO3) and CaCO3 (which is easily dissolved with acetic or hydrochloric acids).

[jmarjorie]

Thanks everyone for your valuable contributions ! Sorry, I slipped up on the solubility of MgSO4 which is very soluble in water(> 100g/Lt)

I came across another way of dissolving the CaSO4: By warming it in (NH4)2SO4