Potassium pentasulfide
| Names | |
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| Other names
Dipotassium pentasulfide, dipotassium sulphide, potassium polysulfide
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| Identifiers | |
3D model (JSmol)
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CompTox Dashboard (EPA)
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| Properties | |
| K2S5 | |
| Molar mass | 238.50 g·mol−1 |
| Appearance | red-orange prisms |
| Structure | |
| orthorhombic | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Potassium pentasulfide is the inorganic compound with the formula K2S5. It is a red-orange solid that dissolves in water. The salt decomposes rapidly in air. It is one of several polysulfide salts with the general formula M2Sn, where M = Li, Na, K and n = 2, 3, 4, 5, 6.[1] The polysulfide salts of potassium and sodium are similar.
Preparation and reactions
The salt is prepared by the addition of elemental sulfur to potassium sulfide. An idealized equation is shown for potassium hydrosulfide:
- 4 KSH + S8 → 2 K2S5 + 2 H2S
The structure consists of zigzag chains of S2−5 paired with K+ ions.[2]
Occurrence
Various polysulfides K2S2 - K2S6 are components of liver of sulfur. Polysulfides, like sulfides, can induce stress corrosion cracking in carbon steel and stainless steel.
References
- ^ F. Fehér" Potassium Disulfide", "Potassium Tetrasulfide" "Potassium Pentasulfide" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 361-367.
- ^ Barbara Kelly and Peter Woodward (1976). "Crystal structure of dipotassium pentasulphide". Journal of the Chemical Society, Dalton Transactions (14): 1314–1316. doi:10.1039/DT9760001314.