Castellani Reaction

“Castellani Reaction” is a chemical reaction of oxidation of sodium sulfide when heated, followed by the reduction of water to ammonia under the action of alkali. Aqueous ammonia can, when heated with copper(II) sulfate and sodium carbonate, produce the oxides of sodium and copper(I) in solution. By adding sodium carbonate, the reaction can remove ammonia from solutions of ammonium salts, such as cyanamide. *Reaction of sodium carbonate with sodium sulfide:* Na2CO3 + 2Na2S → 2NaaS + 3CO2↑ + H2O*