Copper(I) sulfide

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Copper(I) sulfide
Names
IUPAC name
Copper(I) sulfide
Other names
Cuprous sulfide
Chalcocite
Copper glance
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.040.751 Edit this at Wikidata
RTECS number
  • GL8910000
UNII
  • InChI=1S/2Cu.S/q2*+1;-2 checkY
    Key: AQMRBJNRFUQADD-UHFFFAOYSA-N checkY
  • InChI=1/2Cu.S/q2*+1;-2
    Key: AQMRBJNRFUQADD-UHFFFAOYAN
  • [Cu+].[Cu+].[S-2]
Properties
Cu2S
Molar mass 159.16 g/mol
Density 5.6 g/cm3[1][page needed]
Melting point 1,130 °C (2,070 °F; 1,400 K)[2]
insoluble[citation needed]
Solubility in hydrochloric acid slightly soluble[citation needed][quantify]
Solubility in ammonium hydroxide soluble[citation needed][quantify]
Hazards[4]
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g. sodium chlorideFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
0
0
0
Flash point Nonflammable
NIOSH (US health exposure limits):[5]
PEL (Permissible)
 TWA 1 mg/m3 (as Cu)
REL (Recommended)
 TWA 1 mg/m3 (as Cu)
IDLH (Immediate danger)
 TWA 100 mg/m3 (as Cu)
Safety data sheet (SDS) Sigma-Aldrich[3]
Related compounds
Other anions
Other cations
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Copper(I) sulfide is a copper sulfide, a chemical compound of copper and sulfur. It has the chemical formula of Cu2S. It is found in nature as the mineral chalcocite. It has a narrow range of stoichiometry ranging from Cu1.997S to Cu2.000S.[6] Samples are typically black.[citation needed]

Preparation and reactions

[edit]

Cu2S can be prepared by treating copper with sulfur or H2S.[2] The rate depends on the particle size and temperature.[7] Cu2S reacts with oxygen to form SO2:[8][page needed]

2 Cu2S + 3 O2 → 2 Cu2O + 2 SO2

The production of copper from chalcocite is a typical process in extracting the metal from ores. Usually, the conversion involves roasting, to give Cu2O as an intermediate which is further reduced to the metal, and sulfur dioxide:[8][page needed]

Cu2S + O2 → 2 Cu + SO2

Copper(I) oxide readily converts to copper(II) oxide when heated in the presence of oxygen, and to copper metal upon heating in a reducing environment. (cf. Carbothermic reduction)

Structure

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Crystals of chalcocite (mineral form of Cu2S).

Stoichiometric

[edit]

Two forms (a dimorphism) of Cu2S are known. The so-called low temperature monoclinic form ("low-chalcocite") has a complex structure with 96 copper atoms in the unit cell.[9] The hexagonal form, stable above 104 °C (219 °F),[10][page needed] has 24 crystallographically distinct Cu atoms. Its structure has been described as approximating to a hexagonal close packed array of sulfur atoms with Cu atoms in planar 3 coordination. This structure was initially assigned an orthorhombic cell due to the twinning of the sample crystal.

Non-stoichiometric

[edit]

As illustrated by the mineral djurleite, a cuprous sulfide is also known.[clarification needed] With the approximate formula Cu1.96S, this material is non-stoichiometric (range Cu1.934S-Cu1.965S and has a monoclinic structure with 248 copper and 128 sulfur atoms in the unit cell.[9] Cu2S and Cu1.96S are similar in appearance and hard to distinguish one from another.[11]

Phase transition

[edit]

The electrical resistivity increases abruptly at the phase transition point around 104 °C (219 °F), with the precise temperature depending on the stoichiometry.[12][13]

See also

[edit]

References

[edit]
  1. ^ Patnaik, Pradyot (2003). Handbook of inorganic chemicals. New York: McGraw-Hill. ISBN 0-07-049439-8.
  2. ^ a b Greenwood, Norman N.; Earnshaw, Alan (1984). Chemistry of the Elements. Oxford: Pergamon Press. p. 1373. ISBN 978-0-08-022057-4.
  3. ^ "Copper (I) sulfite, SDS". Sigma-Aldrich. Retrieved 18 July 2025.
  4. ^ Sigma-Aldrich Co., Copper(I) sulfide. Retrieved on 18-07-2025.
  5. ^ "NIOSH Pocket Guide to Chemical Hazards".
  6. ^ Potter, R. W. (1977). "An electrochemical investigation of the system copper-sulfur". Economic Geology. 72 (8): 1524–1542. Bibcode:1977EcGeo..72.1524P. doi:10.2113/gsecongeo.72.8.1524.
  7. ^ Blachnik R., Müller A. (2000). "The formation of Cu2S from the elements I. Copper used in form of powders". Thermochimica Acta. 361: 31. doi:10.1016/S0040-6031(00)00545-1.
  8. ^ a b Wiberg, Egon; Wiberg, Nils; Holleman, A. F. (2001). Inorganic chemistry (1st English ed.). San Diego : Berlin ; New York: Academic Press ; De Gruyter. ISBN 0-12-352651-5.
  9. ^ a b Evans, H. T. (1979). "Djurleite (Cu1.94S) and Low Chalcocite (Cu2S): New Crystal Structure Studies". Science. 203 (4378): 356–8. Bibcode:1979Sci...203..356E. doi:10.1126/science.203.4378.356. PMID 17772445. S2CID 6132717.
  10. ^ Wells, A. F. (1984). Structural inorganic chemistry (5th ed.). Oxford [Oxfordshire] : New York: Clarendon Press ; Oxford University Press. ISBN 0-19-855370-6.
  11. ^ Evans H.T. (1981). "Copper coordination in low chalcocite and djurleite and other copper-rich sulfides" (PDF). American Mineralogist. 66 (7–8): 807–818.
  12. ^ Garisto, Dan (2023-08-16). "LK-99 isn't a superconductor — how science sleuths solved the mystery". Nature. 620 (7975): 705–706. Bibcode:2023Natur.620..705G. doi:10.1038/d41586-023-02585-7. PMID 37587284. S2CID 260955242.
  13. ^ Jain, Prashant K. "Phase transition of copper (I) sulfide and its implication for purported superconductivity of LK-99." arXiv preprint arXiv:2308.05222 (2023).