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CaSO₄

Calcium sulfate

IUPAC : Calcium sulfate
SulfateSaltMineralIndustrialEverydayMineral/geologicalFood

Gypsum (CaSO₄·2H₂O) is the raw material of plaster: heated to ~150 °C it loses part of its water to give the hemihydrate which, when mixed with water, returns to its dihydrate form and hardens — this is plaster setting.

3D ball-and-stick representation of Calcium sulfate (formula CaSO₄). Constituent atoms: Ca, S, O.
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Physical properties

Molar mass136.14 g/mol
State at 20 °Csolid
Density2.96 g/cm³
Melting point1733.00 K (1460 °C)
Boiling point—
Solubility (H₂O)0.21 g/100 mL à 20 °C

Structure

Crystal systemOrthorhombic
3D render modeBall-and-stick

Uses and applications

  • Construction plaster (walls, renders, moulds)
  • Medical plaster (immobilising fractures)
  • Blackboard chalk (compressed calcium sulfate)
  • Cement industry (set regulator for Portland cement)
  • Food additive E516 (tofu coagulant)

Constituent elements

20Ca
Calcium
16S
Sulfur
8O
Oxygen

References

PubChem CID24497
CAS7778-18-9
SMILES[Ca+2].[O-]S([O-])(=O)=O
Sources : PubChem CID 24497 · CRC Handbook of Chemistry and Physics