Cobalt sulfide
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Properties | |
CoS (varied) | |
Molar mass | 90.998 g/mol |
Appearance | black solid |
Density | 5.45 g/cm3 |
Melting point | 1195 °C |
insoluble | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Cobalt sulfide is the name for chemical compounds with a formula CoxSy. Well-characterized species include minerals with the formula CoS2 and Co3S4, and the synthetic material Co9S8. In combination with molybdenum, the sulfides of cobalt are used as catalysts for the industrial process called hydrodesulfurization, which is implemented on a large scale in refineries.
Cobalt sulfides precipitate when aqueous solutions of cobalt(II) ions are treated with hydrogen sulfide. This reaction is useful in the purification of cobalt from its ores as well as in qualitative inorganic analysis. In general, the sulfides of cobalt are black, semiconducting, insoluble in water, and nonstoichiometric.
Minerals
The best defined sulfides of cobalt occur as minerals. The rare mineral cattierite has the stoichiometry CoS2. It is isostructural with iron pyrite, featuring disulfide groups, i.e. Co2+S22-. Linnaeite, also rare, has the formula Co3S4 and crystallizes in the spinel motif.[1]
References
- ^ Greenwood, Norman N. (1984). Chemistry of the Elements. Oxford: Pergamon Press. ISBN 0080220576.
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- Cobalt sulfide, NIST Webbook