Calcium Sulfide

Title: Calcium Sulfide
CAS Registry Number: 20548-54-3
Molecular Formula: CaS
Molecular Weight: 72.14
Percent Composition: Ca 55.56%, S 44.45%
Literature References: Pure CaS prepd in the laboratory by heating pure CaCO3 in a stream of H2S + H2 at 1000°: Ehrlich in Handbook of Preparative Inorganic Chemistry vol. 1, G. Brauer, Ed. (Academic Press, New York, 2nd ed., 1963) p 938. Crude calcium sulfide, erroneously called sulfurated lime, calcic liver of sulfur, liver of lime, hepar calcis, made by igniting calcium sulfate with carbonaceous matter. Contains not less than 55% CaS; the balance is calcium sulfate, sulfite and carbonate, and the "ash" from the carbonaceous material. See Mellor's vol III, p 740 (1928). Luminous calcium sulfide or Canton's phosphorus made by igniting a mixture of CaCO3 and S with very small quantities of Bi or Mn salts, etc.: Verneuil, Compt. Rend. 103, 600 (1886); Mellor's, loc. cit.
Properties: White powder if pure; crude and luminous calcium sulfide may be yellowish to pale-gray. Odor of H2S in moist air; unpleasant alkaline taste. Oxidizes in dry air and dec in moist air. mp >2000°. d 2.59. Slightly sol in cold, more sol in hot water with partial decompn; freely sol in solns of ammonium salts; practically insol in alcohol; dec even by weak acids, evolving H2S. Keep well closed.
Melting point: mp >2000°
Density: d 2.59
Use: In phosphors; as lubricant additive. Pure CaS used in electron emitters. Luminous CaS used for making luminous paints or varnishes.
Therap-Cat-Vet: Has been used in chronic suppurative lesions.
Calcium Sulfite Calcium Tartrate Calcium Thiocyanate Calcium Thioglycollate Calcium Thiosulfate

Calcium sulfide
Calcium sulfide
Identifiers
CAS number 20548-54-3 YesY
PubChem 10197613
ChemSpider 8373113 YesY
UNII 1MBW07J51Q N
EC number 243-873-5
KEGG C17392 N
Jmol-3D images Image 1
Image 2
Properties
Molecular formula CaS
Molar mass 72.143 g/mol
Appearance white crystals
hygroscopic
Density 2.59 g/cm3
Melting point 2525 °C
Solubility in water slightly soluble
Solubility insoluble in alcohol
reacts with acid
Refractive index (nD) 2.137
Structure
Crystal structure Halite (cubic), cF8
Space group Fm3m, No. 225
Coordination
geometry
Octahedral (Ca2+); octahedral (S2–)
Hazards
EU Index 016-004-00-0
EU classification Irritant (Xi)
Dangerous for the environment (N)
R-phrases R31, R36/37/38, R50
S-phrases (S2), S28, S61
Main hazards H2S source
NFPA 704
NFPA 704.svg
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Related compounds
Other anions Calcium oxide
Other cations Magnesium sulfide
Strontium sulfide
Barium sulfide
Related sulfides Sodium sulfide
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Calcium sulfide is the chemical compound with the formula CaS. This white material crystallizes in cubes like rock salt. CaS has been studied as a component in a process that would recycle gypsum, a product of flue-gas desulfurization. Like many salts containing sulfide ions, CaS typically has an odour of H2S, which results from small amount of this gas formed by hydrolysis of the salt.

In terms of its atomic structure, CaS crystallizes in the same motif as sodium chloride indicating that the bonding in this material is highly ionic. The high melting point is also consistent with its description as an ionic solid. In the crystal, each S2− ion is surrounded by an octahedron of six Ca2+ ions, and complementarily, each Ca2+ ion surrounded by six S2− ions.