Sciencemadness Discussion Board

Interconversion of sodium and calcium sulphate via salt metathesis reactions

SnailsAttack - 7-3-2022 at 13:27

Have not tested this but it's hypothetically possible.

Written form
1. Sodium sulphate + Calcium acetate -> Sodium acetate + Calcium sulphate
2. Calcium sulphate + Sodium carbonate -> Calcium carbonate + Sodium sulphate
3. Calcium carbonate + Vinegar -> Calcium acetate + Carbon dioxide + Water

Reaction equations
1. Na₂SO₄(aq) + Ca(CH₃COO)₂(aq) -> 2NaCH₃COO(aq) + CaSO₄(s)¹
2. CaSO₄(aq)¹ + Na₂CO₃(aq) -> CaCO₃(s) + Na₂SO₄(aq)
3. CaCO₃(s) + 2CH₃COOH(aq) -> Ca(CH₃COO)₂(aq) + CO₂(g) + H₂O(l)

1) Sodium sulphate is precipitated as calcium sulphate via a metathesis reaction with calcium acetate. Sodium acetate is produced as a byproduct.

2) Calcium sulphate is converted back to sodium sulphate via precipitation of calcium carbonate via a metathesis reaction with sodium carbonate.

3) The calcium acetate is regenerated by reaction of vinegar on the calcium carbonate byproduct.


In summary, sodium sulphate and calcium sulphate can be interconverted through the use of vinegar and sodium carbonate, which are consumed in the reaction series as sodium acetate, water and carbon dioxide.

¹ Note that calcium sulphate is denoted as being insoluble in the first equation but not the second. These are relative solubility values; calcium sulphate is 137x less soluble than calcium acetate, which in turn is 200x more soluble than calcium carbonate.

B(a)P - 7-3-2022 at 18:14

It would be a somewhat interesting little demonstration, though a bit impractical given the volume of water required to make reaction 2 occur.

SWIM - 8-3-2022 at 14:00

So sodium sulfate and calcium acetate eventually yield...
Calcium acetate, water, and carbon dioxide.

Isn't it a lot easier to just not mix your calcium acetate with the sodium sulfate in the first place?

or for a shorter route between calcium acetate and calcium acetate:

Heat calcium acetate in furnace, add vinegar to resulting calcium carbonate.

SnailsAttack - 9-3-2022 at 08:30

Quote: Originally posted by B(a)P  
It would be a somewhat interesting little demonstration, though a bit impractical given the volume of water required to make reaction 2 occur.

could probaly envoke le chateliers principle
Quote: Originally posted by SWIM  
So sodium sulfate and calcium acetate eventually yield...
Calcium acetate, water, and carbon dioxide.

Isn't it a lot easier to just not mix your calcium acetate with the sodium sulfate in the first place?

or for a shorter route between calcium acetate and calcium acetate:

Heat calcium acetate in furnace, add vinegar to resulting calcium carbonate.

the point of this reaction series isn't really to convert calcium acetate to lime, it's to convert sodium sulphate to calcium sulphate and then back again.

the point of this was that i have a metric assload of calcium acetate from leaching rocks with vinegar and want to see if there's any magnesium acetate in it by selectively precipitating the calcium using sodium sulphate.

but then i want my sulphate back