sulfide

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sulfide,

chemical compound containing sulfur and one other element or sulfur and a radicalradical,
in chemistry, group of atoms that are joined together in some particular spatial structure and that take part in most chemical reactions as a single unit. Important inorganic radicals include ammonium, NH4; carbonate, CO3 ; chlorate, ClO3
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. Sulfides may be salts or esters of hydrogen sulfidehydrogen sulfide,
chemical compound, H2S, a colorless, extremely poisonous gas that has a very disagreeable odor, much like that of rotten eggs. It is slightly soluble in water and is soluble in carbon disulfide.
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, H2S, or may be formed directly, e.g., by heating a metal with sulfur. Hydrosulfides are formed when only one of the hydrogens in hydrogen sulfide is replaced with a metal or radical. Soluble metal sulfides are used in preparing dyes, in leather tanning, as depilatory compounds, and as pesticides. Sulfides of antimony, copper, lead, mercury, silver, and zinc are important as ores; the ores are often roasted, yielding sulfur dioxidesulfur dioxide,
chemical compound, SO2, a colorless gas with a pungent, suffocating odor. It is readily soluble in cold water, sparingly soluble in hot water, and soluble in alcohol, acetic acid, and sulfuric acid.
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 and an oxide of the metal. Pyritepyrite
or iron pyrites
, pale brass-yellow mineral, the bisulfide of iron, FeS2. It occurs most commonly in crystals (belonging to the isometric system and usually in the form of cubes and pyritohedrons) but is also found in massive, granular, and stalactite
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 is iron disulfide; tarnish on silver is mostly silver sulfide. In chemical analysis, hydrogen sulfide is often used to precipitate from a solution of metal salts certain metal sulfides that have characteristic colors and solubilities. Carbon disulfidecarbon disulfide,
CS2, liquid organic compound; it is colorless, foul-smelling, flammable, and poisonous. It can be prepared by direct reaction of carbon, e.g., as charcoal, with sulfur. It is a widely used solvent, e.g.
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 is an important solvent for organic compounds.

Sulfide

 

any of several compounds of sulfur with more electropositive elements; sulfides may be regarded as salts of hydrogen sulfide, H2S. There are two sulfide series: the normal sulfides, with the general formula M2S, and the acid sulfides, with the general formula MHS, where M is a monovalent metal.

Sulfides of alkali metals are colorless and dissolve readily in water. Their aqueous solutions are strongly hydrolyzed and exhibit a basic reaction. The action of dilute acids on such sulfides results in liberation of H2S. Sulfides of alkaline-earth metals are colorless, with sparing solubility in water. They liberate H2S in humid air. In other properties they are similar to the sulfides of alkali metals. Both types of sulfides oxidize readily to sulfates.

Sulfides of heavy metals are virtually insoluble in water. Almost all of them are black or brownish black, with the exception of white ZnS, pinkish MnS, yellow CdS, reddish orange Sb2S3, and yellow SnS2. The differing relationship of sulfides to acids and ammonium sulfide is used in chemical analysis.

Many elements form polysulfides, with the general formula M2Sx. These compounds decompose upon heating, with the formation of normal sulfides. Na, K, NH+4, Ca, Sr, and Ba have a particular tendency to form polysulfides.

Sulfides are obtained by (1) direct addition of elements, (2) reaction of aqueous solutions of salts with H2S or (NH4)2S, (3) reaction of hydroxides with H2S, and (4) reduction of sulfates by coal during roasting.

Many sulfides have great practical importance: Na2S, CaS, and BaS are used in the leather industry for tanning, and polysulfides of calcium and barium are used to combat agricultural pests. In addition, PbS, CdS, and ZnS are used as semiconductor materials, and crystals of these and other sulfides are used as semiconductor laser materials. The sulfides of the alkaline-earth metals, along with ZnS and CdS, are bases for luminophors, MoS2 is a solid lubricant, (NH4)2S is an important reagent in qualitative analysis, and FeS2 is a raw material for the production of sulfuric acid.

I. K. MALINA

sulfide

[′səl‚fīd]
(chemistry)
Any compound with one or more sulfur atoms in which the sulfur is connected directly to a carbon, metal, or other nonoxygen atom; for example, sodium sulfide, Na2S.