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|Section2= |Section3= |Section7= |Section8= }} Calcium sulfide is the chemical compound with the formula CaS. This white material crystallizes in cubes like rock salt. CaS has been studied as a component in a process that would recycle gypsum, a product of flue-gas desulfurization. Like many salts containing sulfide ions, CaS typically has an odour of H2S, which results from small amount of this gas formed by hydrolysis of the salt. In terms of its atomic structure, CaS crystallizes in the same motif as sodium chloride indicating that the bonding in this material is highly ionic. The high melting point is also consistent with its description as an ionic solid. In the crystal, each S2− ion is surrounded by an octahedron of six Ca2+ ions, and complementarily, each Ca2+ ion surrounded by six S2− ions. ==Production== CaS is produced by "carbothermic reduction" of calcium sulfate, which entails the conversion of carbon, usually as charcoal, to carbon dioxide: :CaSO4 + 2 C → CaS + 2 CO2 and can react further: :3 CaSO4 + CaS → 4 CaO + 4 SO2 In the second reaction the sulfate (+6 oxidation state) oxidizes the sulfide (-2 oxidation state) to sulfur dioxide (+4 oxidation state), while it is being reduced to sulfur dioxide itself (+4 oxidation state). CaS is also a byproduct in the Leblanc process. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「calcium sulfide」の詳細全文を読む スポンサード リンク
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