Potassium sulfide

Potassium sulfide
Names


IUPAC name Potassium sulfide
Other names Dipotassium monosulfide, Dipotassium sulfide, Potassium monosulfide, Potassium sulfide
Identifiers
CAS Number	1312-73-8^Y
3D model (JSmol)	Interactive image
ChemSpider	142491
ECHA InfoCard	100.013.816
EC Number	215-197-0
PubChem CID	162263
RTECS number	TT6000000
UNII	31R0R7HD0N^Y
UN number	1847 1382
CompTox Dashboard (EPA)	DTXSID70909738
InChI InChI=1S/2K.S/q2*+1;-2 Key: DPLVEEXVKBWGHE-UHFFFAOYSA-N
SMILES [S-2].[K+].[K+]
Properties
Chemical formula	K₂S
Molar mass	110.262 g/mol
Appearance	pure: colourless impure: yellow-brown
Odor	H₂S
Density	1.74 g/cm³
Melting point	840 °C (1,540 °F; 1,110 K)
Boiling point	912 °C (1,674 °F; 1,185 K) (decomposes)
Solubility in water	converts to KSH, KOH
Solubility in other solvents	soluble in ethanol, glycerol insoluble in ether
Magnetic susceptibility (χ)	−60.0·10⁻⁶ cm³/mol
Structure
Crystal structure	antiFluorite
Thermochemistry
Std molar entropy (S^⦵₂₉₈)	105.00 J·mol⁻¹·K⁻¹^[1]
Std enthalpy of formation (Δ_fH^⦵₂₉₈)	-406.2 kJ·mol⁻¹^[2]
Gibbs free energy (Δ_fG^⦵)	-392.4 kJ·mol^[2]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Causes skin burns. Dangerous for the environment
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H314, H400
Precautionary statements	P260, P264, P273, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P391, P405, P501
Related compounds
Other anions	Potassium oxide Potassium selenide Potassium telluride Potassium polonide
Other cations	Lithium sulfide Sodium sulfide Rubidium sulfide Caesium sulfide
Related compounds	Potassium hydrosulfide Potassium sulfite Potassium sulfate Iron(II) sulfide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is ^YN ?) Infobox references

Chemical compound

Potassium sulfide is an inorganic compound with the formula K₂S. The colourless solid is rarely encountered, because it reacts readily with water, a reaction that affords potassium hydrosulfide (KSH) and potassium hydroxide (KOH). Most commonly, the term potassium sulfide refers loosely to this mixture, not the anhydrous solid.

Structure

It adopts "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 sites. Li₂S, Na₂S, and Rb₂S crystallize similarly.^[3]

Synthesis and reactions

It can be produced by heating K₂SO₄ with carbon (coke):

K₂SO₄ + 4 C → K₂S + 4 CO

In the laboratory, pure K₂S may be prepared by the reaction of potassium and sulfur in anhydrous ammonia. ^[4]

Sulfide is highly basic, consequently K₂S completely and irreversibly 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.^[3]

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.^[5]

References

^ CRC Handbook of Chemistry and Physics (95th ed.). CRC Press. 2014. pp. 5–15. ISBN 1482208679.
^ ^a ^b Johnson, G.K.; Steele, W.V. (1981). "The standard enthalpy of formation of potassium sulfide (K₂S) by fluorine bomb calorimetry". The Journal of Chemical Thermodynamics. 13 (10): 985–990. doi:10.1016/0021-9614(81)90075-6.
^ ^a ^b Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
^ Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 360.
^ Shimizu, Takeo. "Fireworks: the Art, Science, and Technique." Pyrotechnica Publications: Austin, 1981. ISBN 0-929388-05-4.