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In
chemistry, a '''sulfide''' ('''sulphide''' in
British and
Canadian English) is a combination of
sulfur with an
oxidation number of -2, with another
chemical element or a
radical thereof. A few
covalent sulfur compounds, such as
carbon disulfide (CS
2) and
hydrogen sulfide (H
2S) are also considered to be sulfides.
Hydrogen sulfide gas has the odor of rotten
eggs, and is also highly
toxic. It is formed biologically in the sediments of
swamps and in the treatment of
sewage sludge by
anaerobic digestion of sulfur containing
proteins, or
bacterial reduction of
sulfates. It also occurs in the emissions of some
volcanoes, and as a byproduct of some industrial processes.
==Uses==
*
Cadmium disulfide (CdS
2) can be used in
photocells.
*
Calcium polysulfide ("
lime sulfur") is a traditional
fungicide in
gardening.
*
Carbon disulfide (CS
2) is sometimes used as a
solvent in industrial chemistry.
*
Silver sulphide (Ag
2S) is formed on
silver electrical contacts operating in an atmosphere rich in
Hydrogen sulfide.
*
Sodium sulfide (Na
2S) is an important industrial chemical, used in manufacture of
kraft paper,
dyes,
leather tanning,
crude petroleum processing, treatment of
heavy metal pollution, and others.
*
Zinc sulfide (ZnS) is used for
lenses and other
optical devices in the
infrared part of the
spectrum.
*
Zinc sulfide with a trace of copper is used for
photoluminescent strips for emergency lighting and luminous watch dials.
*Several metal sulfides are used as
pigments in art, although their use has declined somewhat due to their toxicity. Sulfide pigments include cadmium, mercury, and arsenic.
==Natural occurrence==
Many important
metal ores are sulfides. Significant sulfide
minerals include:
*
arsenopyrite/
mispickel (
arsenic and
iron)
*
argentite (
silver)
*
chalcopyrite (
iron and
copper)
*
cinnabar (
mercury)
*
galena (
lead)
*
pyrite (
iron)
*
realgar (
arsenic)
*
stibnite (
antimony) and
*
zinc blende/
sphalerite (
zinc).
==Safety==
Many sulfides are significantly toxic by inhalation or injection, especially if the metal ion is toxic. Additionally many sulfides, when exposed to a strong mineral
acid, will release toxic hydrogen sulfide - and this includes your stomach acids!
Also, many sulfides are somewhat
flammable, and a few are highly flammable. When a sulfide burns, the fumes usually include toxic
sulfur dioxide (SO
2) gas.
== See also ==
*
sulfate
*
sulfite
da:Sulfid
