Copper(I) sulfide
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| IUPAC name
Copper(I) sulfide
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3D model (JSmol)
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.040.751 |
PubChem CID
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CompTox Dashboard (EPA)
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| 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) | |
| Flash point | Nonflammable |
| NIOSH (US health exposure limits):[5] | |
PEL (Permissible)
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TWA 1 mg/m3 (as Cu) |
REL (Recommended)
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TWA 1 mg/m3 (as Cu) |
IDLH (Immediate danger)
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TWA 100 mg/m3 (as Cu) |
| Safety data sheet (SDS) | Sigma-Aldrich[3] |
| Related compounds | |
Other anions
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Other cations
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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
[edit]
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]- Copper sulfide for an overview of all copper sulfide phases
- Copper monosulfide, CuS
- Chalcocite
- Djurleite
- LK-99 - compound evaluated in 2023 for possible superconductivity
References
[edit]- ^ Patnaik, Pradyot (2003). Handbook of inorganic chemicals. New York: McGraw-Hill. ISBN 0-07-049439-8.
- ^ a b Greenwood, Norman N.; Earnshaw, Alan (1984). Chemistry of the Elements. Oxford: Pergamon Press. p. 1373. ISBN 978-0-08-022057-4.
- ^ "Copper (I) sulfite, SDS". Sigma-Aldrich. Retrieved 18 July 2025.
- ^ Sigma-Aldrich Co., Copper(I) sulfide. Retrieved on 18-07-2025.
- ^ "NIOSH Pocket Guide to Chemical Hazards".
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ Wells, A. F. (1984). Structural inorganic chemistry (5th ed.). Oxford [Oxfordshire] : New York: Clarendon Press ; Oxford University Press. ISBN 0-19-855370-6.
- ^ Evans H.T. (1981). "Copper coordination in low chalcocite and djurleite and other copper-rich sulfides" (PDF). American Mineralogist. 66 (7–8): 807–818.
- ^ 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.
- ^ Jain, Prashant K. "Phase transition of copper (I) sulfide and its implication for purported superconductivity of LK-99." arXiv preprint arXiv:2308.05222 (2023).