Calcium sulfate

Calcium sulfate
General
Other names	Plaster of Paris Gypsum Drierite® whiskers crystal
Molecular formula	CaSO₄
Molar mass	136.142 g/mol (anhydrous)
Appearance	white solid see also text
CAS number	^* (anhydrous)
Properties
Density and phase	22.96 g/cm³, solid
Solubility in water	0.24 g/100 ml (20 °C)
Melting point	1460°C (anhydrous)
Refractive Index	1.57
Mohs hardness	3.5
Structure
Coordination geometry	?
Crystal structure	orthorhombic
Thermodynamic data
Standard enthalpy of formation Δ_fH°_solid	-1434.5 kJ/mol
Standard molar entropy S°_solid	? J.K^–1.mol^–1
Heat of fusion	205.668
Specific Heat Capacity	0.732324 J/g-°C (anhydrous)
Safety data
PEL-TWA (OSHA)	15 mg/m³
RTECS number	WS6920000
NFPA 704
Supplementary data page
Structure & properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Other cations	Magnesium sulfate Strontium sulfate
Related drying agents	Calcium chloride Magnesium sulfate
Related compounds	Plaster of Paris Gypsum
Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Chemical infobox

Calcium sulfate is a common laboratory and industrial chemical. In its anhydrous form, it is sold as a laboratory desiccant under the name Drierite®. The hemihydrate is better known as plaster of Paris, while the dihydrate occurs naturally as gypsum. Depending on the method of calcination of calcium sulfate dihydrate specific hemihydrates are obtained: alpha-hemihydrate and beta-hemihydrate. Alpha-hemihydrate crystals are more prismatic than beta-hemihydrate crystals and when mixed with water form a much stronger and harder superstructure.

External links

Calcium compounds | Sulfates

סידן גופרתי | Сульфат кальция | แคลเซียมซัลเฟต | Сульфат кальцію

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