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Potassium sulfide
From Wikipedia, the free encyclopedia
| Potassium sulfide | |
|---|---|
 |
|
| General | |
| Systematic name | Potassium sulfide |
| Other names | Dipotassium monosulfide, Dipotassium sulfide, Potassium monosulfide |
| Molecular formula | K2S |
| Molar mass | 110.262 g/mol |
| Appearance | pure: colourless impure: yellow-brown |
| CAS number | [1312-73-8] |
| Properties | |
| Density and phase | 1.8 g/cm3 |
| Solubility in water | converts to KSH, KOH |
| Other solvents | |
| Melting point | 840 °C |
| Boiling point | ? °C |
| Structure | |
| Crystal structure | antiFluorite |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | toxic |
| NFPA 704 | |
| R/S statement | R: 31-34 S: 26-45 |
| RTECS number | TT6000000 |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Related compounds | Na2S |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Potassium sulfide is the chemical compound with the formula K2S. It is an inorganic polymer with the so-called antifluorite structure, which means that the small K+ ions occupy the tetrahedral (F−) site in fluorite, and the large S2− centers occupy the eight-coordinate (Ca2+) sites. Li2S, Na2S and Rb2S crystallize similarly.[1]
This salt contains the highly basic anion S2−. As such it hydrolyzes in water according to the following equation:
- K2S + H2O → KOH + KSH
For many purposes, this reaction is inconsequential since the mixture of SH− and OH− behaves as a source of S2−. Other alkali metal sulfides behave similarly.[1]
K2S arises from the reaction of potassium and sulfur. In the laboratory, this synthesis is usually conducted in a solution of anhydrous ammonia.
Sulfurated potash is a poorly defined mixture of potassium sulfide, potassium polysulfide, potassium thiosulfate, and probably potassium bisulfide. Synonyms include hepar sulfuris, Liver of sulfur, sulfurated potash, sulfurated potassa.
Liver of sulfur is mainly used in metalworking to form a patina, turning copper alloys brown.
Liver of sulfur was once used in pharmaceutical preparations such as “white lotion”. At one time sulfurated potash was used to combat arthritis. It is not surprising that it fell into disfavor because sulfides and polysulfides are toxic. Sulfurated potash can also be used for the management of copper in Wilson's disease.[citation needed]
Sulfide salts are toxic.
- ^ a b Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
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