Calcium sulfate

Calcium sulfate
Names
	Other names Sulfate of lime; Plaster of Paris; Drierite; Gypsum
Identifiers
CAS Number	7778-18-9 ; (hemihydrate): 10034-76-1 ; (dihydrate): 10101-41-4 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:31346 ; (dihydrate): CHEBI:32583;
ChEMBL	ChEMBL2106140;
ChemSpider	22905 ;
DrugBank	DB15533;
ECHA InfoCard	100.029.000
EC Number	231-900-3;
E number	E516 (acidity regulators, ...)
Gmelin Reference	7487
KEGG	C13194 ; D09201;
PubChem CID	(dihydrate): 24928;
RTECS number	WS6920000; (dihydrate): MG2360000;
UNII	E934B3V59H ; (hemihydrate): 3RW091J48V ; (dihydrate): 4846Q921YM ;
CompTox Dashboard (EPA)	DTXSID9029699 ;
	InChI InChI=1S/Ca.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2 Key: OSGAYBCDTDRGGQ-UHFFFAOYSA-L ; InChI=1/Ca.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2 Key: OSGAYBCDTDRGGQ-NUQVWONBAU;
	SMILES [Ca+2].[O-]S([O-])(=O)=O;
Properties
Chemical formula	CaSO4
Molar mass	136.14 g/mol (anhydrous); 145.15 g/mol (hemihydrate) ; 172.172 g/mol (dihydrate)
Appearance	white solid
Odor	odorless
Density	2.96 g/cm3 (anhydrous) ; 2.32 g/cm3 (dihydrate)
Melting point	1,460 °C (2,660 °F; 1,730 K) (anhydrous)
Solubility in water	0.26 g/100ml at 25 °C (dihydrate)
Solubility product (Ksp)	4.93 × 10−5 mol2L−2 (anhydrous); 3.14 × 10−5 (dihydrate);
Solubility in glycerol	slightly soluble (dihydrate)
Acidity (pKa)	10.4 (anhydrous) ; 7.3 (dihydrate)
Magnetic susceptibility (χ)	-49.7·10−6 cm3/mol
Structure
Crystal structure	orthorhombic
Thermochemistry
Std molar; entropy (S⦵298)	107 J·mol−1·K−1
Std enthalpy of; formation (ΔfH⦵298)	-1433 kJ/mol
Hazards
NFPA 704 (fire diamond)	1 0 0
Flash point	Non-flammable
	NIOSH (US health exposure limits):
PEL (Permissible)	TWA 15 mg/m3 (total) TWA 5 mg/m3 (resp) [for anhydrous form only]
REL (Recommended)	TWA 10 mg/m3 (total) TWA 5 mg/m3 (resp) [anhydrous only]
IDLH (Immediate danger)	N.D.
Safety data sheet (SDS)	ICSC 1589
Related compounds
Other cations	Magnesium sulfate; Strontium sulfate; Barium sulfate
Related desiccants	Calcium chloride; Magnesium sulfate
Related compounds	Plaster of Paris; Gypsum
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Calcium sulfate (or calcium sulphate) is the inorganic compound with the formula CaSO₄ and related hydrates. In the form of γ-anhydrite (the anhydrous form), it is used as a desiccant. One particular hydrate is better known as plaster of Paris, and another occurs naturally as the mineral gypsum. It has many uses in industry. All forms are white solids that are poorly soluble in water.^[5] Calcium sulfate causes permanent hardness in water.

^ Lebedev, A. L.; Kosorukov, V. L. (2017). "Gypsum Solubility in Water at 25°C" (PDF). Geochemistry International. 55 (2): 171–177. doi:10.1134/S0016702917010062. S2CID 132916752.
^ D.R. Linde (ed.) "CRC Handbook of Chemistry and Physics", 83rd Edition, CRC Press, 2002
^ ^a ^b Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A21. ISBN 978-0-618-94690-7.
^ ^a ^b ^c NIOSH Pocket Guide to Chemical Hazards. "#0095". National Institute for Occupational Safety and Health (NIOSH).
^ Franz Wirsching "Calcium Sulfate" in Ullmann's Encyclopedia of Industrial Chemistry, 2012 Wiley-VCH, Weinheim. doi:10.1002/14356007.a04_555

[1] Lebedev, A. L.; Kosorukov, V. L. (2017). "Gypsum Solubility in Water at 25°C" (PDF). Geochemistry International. 55 (2): 171–177. doi:10.1134/S0016702917010062. S2CID 132916752.

[2] D.R. Linde (ed.) "CRC Handbook of Chemistry and Physics", 83rd Edition, CRC Press, 2002

[b1-3] Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A21. ISBN 978-0-618-94690-7.

[PGCH-4] NIOSH Pocket Guide to Chemical Hazards. "#0095". National Institute for Occupational Safety and Health (NIOSH).

[Ullmanns-5] Franz Wirsching "Calcium Sulfate" in Ullmann's Encyclopedia of Industrial Chemistry, 2012 Wiley-VCH, Weinheim. doi:10.1002/14356007.a04_555

[1]

[2]

[3]

[4]

[5]

Names


Other names Sulfate of lime Plaster of Paris Drierite Gypsum
Identifiers
CAS Number	7778-18-9^Y (hemihydrate): 10034-76-1^Y (dihydrate): 10101-41-4^Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:31346^Y (dihydrate): CHEBI:32583
ChEMBL	ChEMBL2106140
ChemSpider	22905^Y
DrugBank	DB15533
ECHA InfoCard	100.029.000
EC Number	231-900-3
E number	E516 (acidity regulators, ...)
Gmelin Reference	7487
KEGG	C13194^N D09201
PubChem CID	(dihydrate): 24928
RTECS number	WS6920000 (dihydrate): MG2360000
UNII	E934B3V59H^Y (hemihydrate): 3RW091J48V^Y (dihydrate): 4846Q921YM^Y
CompTox Dashboard (EPA)	DTXSID9029699
InChI InChI=1S/Ca.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2^Y Key: OSGAYBCDTDRGGQ-UHFFFAOYSA-L^Y InChI=1/Ca.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2 Key: OSGAYBCDTDRGGQ-NUQVWONBAU
SMILES [Ca+2].[O-]S([O-])(=O)=O
Properties
Chemical formula	CaSO₄
Molar mass	136.14 g/mol (anhydrous) 145.15 g/mol (hemihydrate) 172.172 g/mol (dihydrate)
Appearance	white solid
Odor	odorless
Density	2.96 g/cm³ (anhydrous) 2.32 g/cm³ (dihydrate)
Melting point	1,460 °C (2,660 °F; 1,730 K) (anhydrous)
Solubility in water	0.26 g/100ml at 25 °C (dihydrate)^[1]
Solubility product (K_sp)	4.93 × 10⁻⁵ mol²L⁻² (anhydrous) 3.14 × 10⁻⁵ (dihydrate) ^[2]
Solubility in glycerol	slightly soluble (dihydrate)
Acidity (pK_a)	10.4 (anhydrous) 7.3 (dihydrate)
Magnetic susceptibility (χ)	-49.7·10⁻⁶ cm³/mol
Structure
Crystal structure	orthorhombic
Thermochemistry
Std molar entropy (S^⦵₂₉₈)	107 J·mol⁻¹·K⁻¹ ^[3]
Std enthalpy of formation (Δ_fH^⦵₂₉₈)	-1433 kJ/mol^[3]
Hazards
NFPA 704 (fire diamond)	1 0 0
Flash point	Non-flammable
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 15 mg/m³ (total) TWA 5 mg/m³ (resp) [for anhydrous form only]^[4]
REL (Recommended)	TWA 10 mg/m³ (total) TWA 5 mg/m³ (resp) [anhydrous only]^[4]
IDLH (Immediate danger)	N.D.^[4]
Safety data sheet (SDS)	ICSC 1589
Related compounds
Other cations	Magnesium sulfate Strontium sulfate Barium sulfate
Related desiccants	Calcium chloride Magnesium sulfate
Related compounds	Plaster of Paris Gypsum
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is ^YN ?) Infobox references