Caesium sulfide

Cesium sulfide is an inorganic salt with a chemical formula Cs2S. It is a strong alkali in aqueous solution. In the air, cesium sulfide emits rotten egg smelling hydrogen sulfide.

Production
Similar to sodium sulfide, anhydrous cesium sulfide can be produced by reacting cesium and sulfur in THF. It needs ammonia or naphthalene to react.
 * 2 Cs + S -> Cs2S

By dissolving hydrogen sulfide into cesium hydroxide solution, it will produce cesium bisulfide, then it will produce cesium sulfide too. .
 * CsOH + H2S -> CsHS + H2O
 * CsHS + CsOH -> Cs2S + H2O