Calcium sulfate
Calcium sulfate is a chemical compound with the chemical formula CaSO4. 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,[1] and for soil in plant growth due to nutrient sources of calcium and sulfur.
Preparation
[change | change source]It is made when calcium hydroxide reacts with sulfuric acid to make calcium sulfate dihydrate.
- The balanced chemical equation is:
- Ca(OH)2 + H2SO4 → CaSO4 + 2H2O
- Then it hydrates to calcium sulfate dihydrate:
- CaSO4 + 2H2O → CaSO4 · 2H2O
Reactions with calcium sulfate
[change | change source]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:
- CaSO4 · 2H2O + heat → CaSO4 · 1/2 H2O + 1+1/2 H2O↑
- While the balanced chemical equation for the hemihydrate is:
- CaSO4 · 1/2 H2O + heat → CaSO4 + 1/2 H2O↑
Related pages
[change | change source]References
[change | change source]- ↑ "Calcium Sulfate – BAKERpedia". Retrieved 2026-02-27.