Calcium sulfate

Calcium sulfate is a chemical compound with the chemical formula . This compound contains calcium and sulfate ions. Its molar mass is around 136.141 g/mol (anhydrous). It can form the dihydrate (gypsum) or hemihydrate (plaster of Paris) salt when hydrated (depending how much water it has absorbed from the moisture and the temperature). It used as a building material in drywall, an ingredient in Portland cement, a food additive in some foods, and for soil in plant growth due to nutrient sources of calcium and sulfur.

Preparation
It is made when calcium hydroxide reacts with sulfuric acid to make calcium sulfate dihydrate.
The balanced chemical equation is:

Then it hydrates to calcium sulfate dihydrate:

Reactions with calcium sulfate
It can be dehydrated by heating, which turns calcium sulfate dihydrate or hemihydrate into calcium sulfate anhydrous.
The balanced chemical equation for the dihydrate is:
 + heat →  ·   +  
While the balanced chemical equation for the hemihydrate is:
 ·   + heat →  +  

Related pages
Potassium sulfate
Calcium sulfide

References

Category:Calcium compounds
Category:Sulfates