Calcium sulfate

Molecular Structure of Calcium sulfate (CAS NO.7778-18-9):

IUPAC Name: calcium sulfate 
Empirical Formula: CaSO₄
Molecular Weight: 136.1406
H bond acceptors: 4
H bond donors: 2
Freely Rotating Bonds: 0
Polar Surface Area: 82.98Ų
Enthalpy of Vaporization: 62.94 kJ/mol
Boiling Point: 330 °C at 760 mmHg
Vapour Pressure: 3.35E-05 mmHg at 25°C
InChI
InChI=1/Ca.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2
Smiles
S(=O)(=O)([O-])[O-].[Ca+2]
EINECS: 231-900-3
Melting point: 1450 °C
Storage temp: Store at RT.
Sensitive Moisture Sensitive
Merck: 14,1706
Stability: Stable. Incompatible with aluminium, strong acids
Product Categories: Inorganics; Calcium Salts; CalciumMetal and Ceramic Science; Inorganic Salts; Salts; Synthetic Reagents
Synonyms: Anhydrous calcium sulfate ; Anhydrous gypsum ; Anhydrous sulfate of lime ; Basic calcium sulfate ; Calcium sulfate (1:1) ; Calcium sulfate, anhydrous ; Franklin Fiber H 45 ; Sulfuric acid, calcium salt (1:1) ; Surfuric acid calcium(2+) salt (1:1)

 Calcium sulfate (CAS NO.7778-18-9) is a common laboratory and industrial chemical. In the form of γ-anhydrite (the nearly anhydrous form), it is used as a desiccant. It is also used as a coagulant in products like tofu.

Hazard Codes: T,N,Xi
Risk Statements: 49-42/43-51/53-36/37
R49:May cause cancer by inhalation. 
R42/43:May cause sensitization by inhalation and skin contact. 
R51/53:Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment. 
R36/37:Irritating to eyes and respiratory system.
Safety Statements: 53-22-36/37-45-60-24/25-36-26
S53:Avoid exposure - obtain special instructions before use. 
S22:Do not breathe dust. 
S36/37:Wear suitable protective clothing and gloves. 
S45:In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) 
S60:This material and its container must be disposed of as hazardous waste. 
S24/25:Avoid contact with skin and eyes. 
S36:Wear suitable protective clothing. 
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice.
RIDADR: UN 3077 9/PG 3
WGK Germany: 1
RTECS: WS6920000
F: 3

OSHA PEL: Total Dust: 15 mg/m³; Respirable Fraction: 5 mg/m³
ACGIH TLV: TWA (nuisance particulate) 10 mg/m³ of total dust (when toxic impurities are not present, e.g., quartz <1%)
DFG MAK: 6 mg/m³

Heating gypsum to between 100 °C and 150 °C (302 °F) partially dehydrates the mineral by driving off approximately 75% of the water contained in its chemical structure. The temperature and time needed depend on ambient partial pressure of H₂O. Temperatures as high as 170 °C are used in industrial calcination, but at these temperatures γ-anhydrite begins to form.

 In the natural state, unrefined Calcium sulfate (CAS NO.7778-18-9) is a translucent, crystalline white rock. The hemihydrate (CaSO4.~0.5H2O) is better known as plaster of Paris, while the dihydrate (CaSO4.2H2O) occurs naturally as gypsum. The main sources of Calcium sulfate (CAS NO.7778-18-9) are naturally occurring gypsum and anhydrite which occur at many locations worldwide as evaporites. These may be extracted by open-cast quarrying or by deep mining. World production of natural gypsum is around 127 million tonnes per annum.