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.Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
This salt contains the highly basic anion S²⁻, which completely hydrolyzes in water according to the following equation:

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.
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.Shimizu, Takeo. "Fireworks: the Art, Science, and Technique." Pyrotechnica Publications: Austin, 1981. ISBN 0-929388-05-4.

See also

Liver of sulfur