Sources
Help build the largest human-edited directory on the web.
Submit a site - Become an editor
Wikipedia. Licensed under the GNU Free Documentation License.
Are you an expert in this subject? Join the discussion and share your knowledge at Wikipedia.org.
Calcium sulfide
From Wikipedia, the free encyclopedia
| Calcium sulfide | |
|---|---|
 |
|
| General | |
| Systematic name | Calcium sulfide |
| Other names | calcium monosulfide, hepar calcies, sulfurated lime oldhamite |
| Molecular formula | CaS |
| Molar mass | 72.14 g/mol |
| Appearance | White solid |
| CAS number | [20548-54-3] |
| Properties | |
| Density and phase | 2600 kg m-3, solid |
| Solubility in water | hydrolysis |
| Melting point | 2400 °C (2673 K) |
| Boiling point | |
| Structure | |
| Coordination geometry |
Octahedral |
| Crystal structure | Sodium chloride |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | H2S source |
| NFPA 704 |
0
1
0
|
| R/S statement | R: 31-36/37/38-50
|
| 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 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 |
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
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.[1]
- ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
 |
This inorganic compound-related article is a stub. You can help Wikipedia by expanding it. |