| Potassium sulfide | |
|---|---|
 |
|
| IUPAC name |
Potassium sulfide
|
| Other names | Dipotassium monosulfide, Dipotassium sulfide, Potassium monosulfide |
| Identifiers | |
| CAS number | 1312-73-8 |
| RTECS number | TT6000000 |
| Properties | |
| Molecular formula | K2S |
| Molar mass | 110.262 g/mol |
| Appearance | pure: colourless impure: yellow-brown |
| Density | 1.8 g/cm3 |
| Melting point |
840 °C |
| Boiling point |
decomposes |
| Solubility in water | converts to KSH, KOH |
| Solubility in other solvents | soluble in ethanol and glycerol |
| Structure | |
| Crystal structure | antiFluorite |
| Hazards | |
| R-phrases | 31-34 |
| S-phrases | 26-45 |
| Related compounds | |
| Related compounds | Na2S |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
| Infobox references | |
Potassium sulfide is the chemical compound with the formula K2S. It is an inorganic polymer with the "antifluorite structure," which means that the small K+ ions occupy the tetrahedral (F−) sites in fluorite, and the larger S2− centers occupy the eight-coordinate (Ca2+) sites. Li2S, Na2S, and Rb2S crystallize similarly.[1]
This salt contains the highly basic anion S2−, which completely 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.
Use in fireworks
Potassium sulfides are formed when black powder is burned, and are important intermediates in many pyrotechnic effects, such as senko hanabi and some glitter formulations. The compound is not added directly to the fireworks but rather forms during their combustion.[2]
See also
References
- ^ a b Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
- ^ Shimizu, Takeo. "Fireworks: the Art, Science, and Technique." Pyrotechnica Publications: Austin, 1981. ISBN 0-929388-05-4.
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