Calcium sulfide

Short description: Chemical compound of formula CaS

Calcium sulfide

Names
IUPAC name

Calcium sulfide

Other names

Calcium monosulfide,
Hepar calcies,
Sulfurated lime
Oldhamite

Identifiers

CAS Number

* 20548-54-3 Y

3D model (JSmol)

* Interactive image
* Interactive image

ChEBI |

* CHEBI:81055

ChemSpider |

* 8373113 Y

EC Number |

* 243-873-5

KEGG |

* C17392 Y

PubChem CID

* 10197613

UNII |

* 1MBW07J51Q Y

InChI

* InChI=1S/Ca.S/q+2;-2 Y

Key: AGVJBLHVMNHENQ-UHFFFAOYSA-N Y

* InChI=1/Ca.S/rCaS/c1-2

Key: JGIATAMCQXIDNZ-WSLZQIQFAE

* InChI=1/Ca.S/q+2;-2

Key: AGVJBLHVMNHENQ-UHFFFAOYAE

SMILES

* [Ca]=S

* [Ca+2].[S-2]

Properties

Chemical formula

| CaS
Molar mass | 72.143 g/mol
Appearance  | white crystals
hygroscopic
Density | 2.59 g/cm3
Melting point |  2,525 °C (4,577 °F; 2,798 K)

Solubility in water

| Hydrolyses
Solubility | Insoluble in alcohol
reacts with acid

Refractive index (nD)

| 2.137
Structure

Crystal structure

| Halite (cubic), cF8

Space group

| Fm3m, No. 225

Lattice constant

a = 569.08 nm[1]

Coordination geometry

| Octahedral (Ca2+); octahedral (S2−)
Hazards
Main hazards | Reacts with water to release H2S
GHS pictograms |
GHS Signal word | Warning

GHS hazard statements

| H315, H319, H335, H400

GHS precautionary statements

| P261, P273, P305+351+338
NFPA 704 (fire diamond)  |

Related compounds

Other anions

| Calcium oxide

Other cations

| Magnesium sulfide
Strontium sulfide
Barium sulfide

Related sulfides

| Sodium sulfide

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

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.

## Contents

* 1 Production
* 2 Reactivity and uses
* 3 Natural occurrence
* 4 See also
* 5 References

## Production

CaS is produced by carbothermic reduction of calcium sulfate, which entails the conversion of carbon, usually as charcoal, to carbon dioxide:

CaSO4 \+ 2 C → CaS + 2 CO2

and can react further:

3 CaSO4 \+ CaS → 4 CaO + 4 SO2

In the second reaction the sulfate (+6 oxidation state) oxidizes the sulfide (−2 oxidation state) to sulfur dioxide (+4 oxidation state), while it is being reduced to sulfur dioxide itself (+4 oxidation state).

CaS is also a byproduct in the Leblanc process, a once major industrial process for producing sodium carbonate. In that process sodium sulfide reacts with calcium carbonate:[2]

Na2S + CaCO3 → CaS + Na2CO3

Millions of tons of this calcium sulfide byproduct was discarded, causing extensive pollution and controversy.[3]

Milk of lime, Ca(OH)2, reacts with elemental sulfur to give a "lime-sulfur", which has been used as an insecticide. The active ingredient is probably a calcium polysulfide, not CaS.[4]

## Reactivity and uses

Calcium sulfide decomposes upon contact with water, including moist air, giving a mixture of Ca(SH)2, Ca(OH)2, and Ca(SH)(OH).

CaS + H2O → Ca(SH)(OH)
Ca(SH)(OH) + H2O → Ca(OH)2 \+ H2S

It reacts with acids such as hydrochloric acid to release toxic hydrogen sulfide gas.

CaS + 2 HCl → CaCl2 \+ H2S

Calcium sulfide is phosphorescent, and will glow a blood red for up to an hour after a light source is removed.[5]

As a noxious byproduct of the Leblanc process, it can be converted to calcium carbonate and hydrogen sulfide, the latter of which can be used as a sulfur source for the lead chamber process to produce the sulfuric acid necessary for the Leblanc process:

CaS(s) + CO
2(g) + H
2O(l) → CaCO
3(s) + H
2S(g)

## Natural occurrence

Oldhamite is the name for mineralogical form of CaS. It is a rare component of some meteorites and has scientific importance in solar nebula research.[6][7] Burning of coal dumps can also produce the compound.[8]

## See also

* Glossary of meteoritics

## References

1. ↑ "ChemicalBook". https://www.chemicalbook.com/ChemicalProductProperty_EN_CB3391370.htm.
2. ↑ Christian Thieme (2000). "Sodium Carbonates". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a24_299. ISBN 978-3527306732.
3. ↑ Kiefer, David M. (January 2002). "It was all about alkali". Today's Chemist at Work 11 (1): 45–6. http://pubs.acs.org/subscribe/journals/tcaw/11/i01/html/01chemchron.html.
4. ↑ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
5. ↑ "Red Glow in the Dark Powder - Calcium Sulfide". https://www.technoglowproducts.com/red-glow-in-the-dark-powder-calcium-sulfide/.
6. ↑ "Oldhamite". https://www.mindat.org/min-2970.html.
7. ↑ "List of Minerals". 21 March 2011. https://www.ima-mineralogy.org/Minlist.htm.
8. ↑ Kruszewski, Ł. (January 2006). "Oldhamite-periclase-portlandite-fluorite assemblage and coexisting minerals of burnt dump in Siemianowice Ślaskie-Dabrówka Wielka area (Upper Silesia, Poland) - preliminary report". Mineralogia Polonica - Special Papers 28: 118–120. https://www.researchgate.net/publication/285329328.

* v
* t
* e

Calcium compounds

* CaAl2O4
* CaB6
* CaBr2
* Ca(BrO3)2
* CaC2
* CaCN2
* Ca(CN)2
* CaCO3
* CaC2O4
* CaCl2
* Ca(ClO)2
* Ca(ClO3)2
* CaCrO4
* CaF2
* CaH2
* Ca(HCO3)2
* CaH2S2O6
* CaI2
* Ca(IO3)2
* Ca(MnO4)2
* CaN6
* Ca(NO3)2
* CaO
* CaO2
* Ca(OH)2
* CaP
* CaS
* CaSO3
* CaSO4
* CaSe
* CaSi
* CaSi2
* CaTiO3
* Ca2P2O7
* Ca2SiO4
* Ca3Al2O6
* Ca3(AsO4)2
* Ca3(BO3)2
* Ca3(C6H5O7)2
* Ca3N2
* Ca3P2
* Ca4(PO4)2O
* Ca3(PO4)2
* Ca(H2PO4)2
* CaHPO4
* C36H70CaO4

* v
* t
* e

Sulfides

| H2S
H2S2 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | He

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Li2S | BeS |  |  |  |  |  |  |  |  |  |  | B2S3 | CS2
COS | (NH4)SH | O | F | Ne
Na2S
Na2Sx | MgS |  |  |  |  |  |  |  |  |  |  | Al2S3 | SiS
SiS2 | PxSy | S | Cl | Ar
K2S | CaS | Sc2S3 | TiS2 | V | CrS
Cr2S3 | MnS
MnS2 | FeS
Fe3S4 | CoS | NiS | Cu2S
CuS | ZnS | GaS
Ga2S3 | GeS
GeS2 | As2S3
As4S3 | SeS2 | Br | Kr
Rb2S | SrS | Y2S3 | ZrS2 | NbS2 | MoS2 | Tc | Ru | Rh2S3 | PdS | Ag2S | CdS | In2S3 | SnS
SnS2 | Sb2S3
Sb2S5 | TeS2 | I | Xe
Cs2S | BaS | *  | HfS2 | TaS2 | WS2
WS3 | ReS2
Re2S7 | Os | Ir2S3
IrS2 | PtS
PtS2 | Au2S
Au2S3 | HgS | Tl2S | PbS
PbS2 | Bi2S3 | Po | At | Rn
Fr | Ra | **  | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | Cn | Nh | Fl | Mc | Lv | Ts | Og |  |  |  |  |  |  |  |
|  | ↓ |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| * | La2S3 | CeS
Ce2S3 | Pr2S3 | Nd2S3 | Pm2S3 | SmS
Sm2S3 | Eu2S3 | Gd2S3 | Tb2S3 | Dy2S3 | Ho2S3 | Er2S3 | Tm2S3 | Yb2S3 | Lu2S3 |
| ** | Ac | ThS2 | Pa | US2 | Np | Pu | Am | Cm | Bk | Cf | Es | Fm | Md | No | Lr |

* v
* t
* e

Meteorites and meteoritics

Meteorite...|

* Glossary
* Fall
* bolide
* impactite
* statistics
* strewn field
* Find
* hunting
* Largest
* Micrometeorite
* Notable
* Parent body

Classification|

| By type, class,
clan, group
and grouplet|

| Chondrite|

* Carbonaceous
* CB
* CH
* CI
* CK
* CM
* CO
* CR
* CV
* C ungrouped
* Enstatite
* EH
* EL
* Kakangari
* Ordinary
* H
* L
* LL
* Rumuruti

|

Achondrite|

| Primitive|

* Acapulcoite
* Brachinite
* IAB
* IIICD
* Lodranite
* Ureilite
* Winonaite

|

Asteroidal|

* Angrite
* Aubrite
* HED
* Diogenite
* Eucrite
* Howardite

Lunar|

* Impact breccia
* Mare basalts
* List

Martian|

* Balsaltic Breccia
* NWA 7034
* Chassignites
* Kaidun
* Nakhlites
* Orthopyroxenite
* ALH84001
* Shergottites
* Martian meteorites list
* Meteorites on Mars list

Iron|

* IC
* IIAB
* IIC
* IID
* IIE
* IIG
* IIIAB
* IIIE
* IIIF
* IVA
* IVB

Stony-iron|

* Mesosiderite
* Pallasite
* Main group
* Eagle Station
* Pyroxene

Structural|

* Ataxite
* Hexahedrite
* Octahedrite

Obsolete terms|

* Amphoterite
* Nonmagmatic meteorite

Mineralogy and
petrology|

* Characteristics
* shock
* TKW
* weathering
* Grains
* chondrule
* presolar
* Minerals
* Ca–Al-rich inclusion
* extraterrestrial materials
* meteoric iron
* Patterns
* Neumann lines
* Widmanstätten
* CI1 fossils

Lists|

* Meteorites by
* find location
* name
* type
* Awards
* Journals
* Organizations

* See also: Asteroid
* Atmospheric entry
* Comet
* Impact event
* Meteor
* shower
* Meteoroid
* Near-Earth object

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*[CID]: Compound ID
*[H315]: Causes skin irritation
*[H319]: Causes serious eye irritation
*[H335]: May cause respiratory irritation
*[H400]: Very toxic to aquatic life
*[P261]: Avoid breathing dust/fume/gas/mist/vapours/spray
*[P273]: Avoid release to the environment
*[P305+351+338]: IF IN EYES: Rinse continuously with water for several minutes. Remove contact lenses if present and easy to do – continue rinsing
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