Сульфид кальция

Химические свойства

CALCIUM SULFIDE is OFF-WHITE POWDER

Физические свойства

Calcium sulfide is slightly soluble in water but insoluble in alcohol. It reacts with acids, producing hydrogen sulfide gas. Calcium sulfide is pale yellow to light gray with a bitter taste. It is hygroscopic, producing an odor of H2S in moist air.

Вхождение

Calcium sulfide occurs in nature as the mineral oldhamite. It has several applications. The ‘luminous’ calcium sulfide is used in phosphors, luminous paints and varnishes. Calcium sulfide also is used as an additive to lubri cants; and as a flotation agent in ore extraction.

Использование

CALCIUM SULFIDE is used in electron emitters. Luminous CaS used for making luminous paints or varnishes.

Подготовка

Calcium sulfide can be prepared by the direct reaction of the elements, calcined in an inert atmosphere, at a 1:1.05 molecular ratio:
Ca＋S＋heat→CaS
This white material crystallizes in a cubic structurelike rock salt and the bonding is highly ionic. This is consistent with its description as an ionic solid. CaS can also be produced by the “carbothermic reduction” of calcium sulfate, which entails the conversion of carbon, usually as charcoal, to CO2:
CaSO4＋ 2C→CaS＋ 2CO2
This can react further:
3CaSO4＋ CaS→4CaO＋ 4SO2
Thus, this type of preparation cannot be used to prepare a pure CaS salt.
Calcium sulfide is available commercially as the pure sulfide as well as the polysulfide due to its extensive usage in the past as an insecticide both agriculturally and in home gardens.

Общее описание

Crystal structure of CaS is cubic. Electrical conductivity of calcium sufide in the temperature range of 650^oC-1000^oC was studied in great detail. It was concluded that CaS could be used as a potential electrolyte in a sulfur concentration cell.2