Initial language selection is based on your web browser preferences.
**Molecular formula (calcium sulphate):** CaSO₄
**Molecular formula (gypsum):** CaSO₄·2H₂O
**Molar mass:** 136,14 g/mol (anhydrous)
**Molar mass:** 172,17 g/mol (dihydrate)
**Information:** Calcium sulphate is a white, crystalline substance poorly soluble in water. It is an ionic compound containing calcium cation Ca²⁺ and sulphated anion SO₄²⁻. It causes permanent water hardness.
**Use:** Calcium sulphate is used in the building industry. From its heating the gypsum, burnt gypsum (CaSO₄·½H₂O) is formed which hydrates with water. This is used, for example, when repairing plasters. It is also used for the production of plasterboard.
**Occurrence:** Calcium sulphate dihydrate occurs in nature as a mineral, gypsum.