Calcium sulfide
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| Calcium sulfide | |
|---|---|
| General | |
| Systematic name | Calcium (II) sulfide |
| Other names | calcium monosulfide, hepar calcies, sulfurated lime oldhamite |
| Molecular formula | CaS |
| Molar mass | 72.14 g/mol |
| Appearance | White crystalline solid |
| CAS number | [20548-54-3] |
| Properties | |
| Density and phase | 2600 kg m-3, solid |
| Solubility in water | Decomposes |
| Melting point | 2400 °C (2673 K) |
| Boiling point | |
| Structure | |
| Coordination geometry | Octahedral |
| Crystal structure | |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | N/A |
| NFPA 704 | |
| Flash point | N/A |
| R/S statement | R: N/A S: N/A |
| RTECS number | N/A |
| Supplementary data page | |
| Structure and properties | N/A |
| Thermodynamic data | N/A |
| Spectral data | N/A |
| Related compounds | |
| Other anions | CaO |
| Other cations | MgS, BaS |
| Related salts | Na2S |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references | |
Calcium sulfide is the chemical compound with the formula CaS. This white material crystallizes in cubes, with the rock salt structure. It is studied as a reactant in a process that would recycle gypsum, a product of coal processing that would otherwise be disposed of in landfills.
Contents |
[edit] Production and uses
CaS is produced by carbothermic reduction of the more common calcium compound, calcium sulfate:
- CaSO4 + 2 C → CaS + 2 CO2
and can react further:
- CaSO4 + 2 CaS → 2 CaO + SO2
[edit] 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) + H2S
- Ca(SH)(OH) + H2O → Ca(OH)2 + H2S
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.<ref>Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.</ref>
[edit] References
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[edit] External links
