Copper(I) sulfide is a copper sulfide, a chemical compound of copper and sulfur. It has the chemical compound Cu2S. It is found in nature as the mineral chalcocite. It has a narrow range of stoichiometry ranging from Cu1.997S to Cu2.000S.[4] Samples are typically black.
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IUPAC name
Copper(I) sulfide
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Identifiers | |
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3D model (JSmol)
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ChEBI |
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ECHA InfoCard | 100.040.751 |
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Properties | |
Cu2S | |
Molar mass | 159.16 g/mol |
Density | 5.6 g/cm3[1] |
Melting point | 1,130 °C (2,070 °F; 1,400 K)[2] |
insoluble | |
Solubility | slightly soluble in HCl; soluble in NH4OH; dissolves in KCN; decomposes in HNO3, H2SO4 |
Hazards | |
Flash point | Nonflammable |
NIOSH (US health exposure limits): | |
PEL (Permissible)
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TWA 1 mg/m3 (as Cu)[3] |
REL (Recommended)
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TWA 1 mg/m3 (as Cu)[3] |
IDLH (Immediate danger)
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TWA 100 mg/m3 (as Cu)[3] |
Related compounds | |
Other anions
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Copper(I) oxide Copper(I) selenide |
Other cations
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Nickel(II) sulfide Copper(II) sulfide Zinc sulfide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
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Cu2S can be prepared by treating copper with sulfur or H2S.[2] The rate depends on the particle size and temperature.[5] Cu2S reacts with oxygen to form SO2:[6]
The production of copper from chalcocite is a typical process in extracting the metal from ores. Usually, the conversion involves roasting, to give Cu2O and sulfur dioxide:[6]
Cuprous oxide readily converts to copper metal upon heating.
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.[7] The hexagonal form, stable above 104 °C,[8] 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.
As illustrated by the mineral djurleite, a cuprous sulfide is also known. 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.[7] Cu2S and Cu1.96S are similar in appearance and hard to distinguish one from another.[9]
The electrical resistivity increases abruptly at the phase transition point around 104 °C, with the precise temperature depending on the stoichiometry.[10][11]