Copper sulfide (Cu2S) (22205-45-4) Physical and Chemical Properties
Copper sulfide (Cu2S)
Copper(I) sulfide is an inorganic metal sulfide commonly used as a conductive pigment, catalyst precursor and solid lubricant in coatings, electrodes and materials research.
| CAS Number | 22205-45-4 |
| Family | Metal sulfides |
| Typical Form | Powder or crystalline solid |
| Common Grades | EP |
Copper sulfide (Cu2S) is an inorganic binary sulfide of copper in which copper occurs primarily in the +1 oxidation state (cuprous sulfide). Structurally it is a non-stoichiometric/defect-containing inorganic solid in the family of copper chalcogenides; the compound crystallizes in structures related to the mineral chalcocite and displays metallic to semiconducting electronic behavior depending on stoichiometry and defects. The bonding network is dominated by Cu–S interactions with significant covalent character mixed with metallic conduction pathways, producing low topological polar surface area and no conventional H-bonding features.
Chemically, Cu2S is a poorly soluble, low-polarity inorganic solid that is chemically stable under neutral, anoxic conditions but is susceptible to oxidation, sulfidation changes, and acid attack. As a sulfide of a monovalent transition metal, it is not an acid or base in the molecular sense; rather, its reactivity in aqueous environments is governed by redox, protonation of sulfur (acid attack producing sulfide-derived species), and complexation or oxidation of copper to higher oxidation states (Cu(II)). The material displays low aqueous mobility under reducing conditions but can generate soluble copper species under oxidizing or strongly acidic conditions, with attendant toxicity considerations due to released copper ions.
Industrially and geologically, Cu2S is encountered as the mineral chalcocite and as a processed material in metallurgy and catalysis. Typical functional roles include use as a pigment component, as a component in certain electrode materials, solid lubricant formulations, and as a heterogeneous catalyst precursor. Common commercial grades reported for this substance include: EP.
Basic Physical Properties
Density
No experimentally established value for this property is available in the current data context. Qualitatively, Cu2S as a dense sulfide mineral/crystalline solid has substantially higher mass density than typical organic solids; density depends on crystallographic polymorph and defect concentration and is routinely reported in materials-characterization literature for specific samples.
Melting or Decomposition Point
No experimentally established value for this property is available in the current data context. Technically, copper(I) sulfide exhibits structural transitions and decomposition behavior on heating; thermal behaviour is dominated by phase transitions and oxidation rather than a simple, well-defined molecular melting point for a covalent/metallic solid.
Solubility in Water
No experimentally established value for this property is available in the current data context. Qualitatively, Cu2S is effectively insoluble in water under neutral to mildly reducing conditions; its apparent aqueous solubility is governed by surface oxidation, particle size, and redox conditions. Under strongly oxidizing or strongly acidic conditions it can yield soluble copper species (Cu+ or oxidized to Cu2+) and sulfur-containing aqueous products.
Solution pH (Qualitative Behavior)
No experimentally established value for this property is available in the current data context. Because Cu2S is essentially insoluble in water, an intrinsic aqueous pH is not applicable; when particles are suspended or when the solid is attacked by acids, the resulting solution pH will reflect the acidity of the medium and any sulfur species formed (e.g., protonation of sulfide under strong acid).
Chemical Properties
Acid–Base Behavior
Copper(I) sulfide does not act as a classical Bronsted acid or base in bulk form. In aqueous or acidic environments, protonation of sulfide sites (S2− → H2S/H S− species under strong acid) or oxidation of copper can occur. Under strong acid the solid may be consumed and hydrogen sulfide or other reduced sulfur species can be released; under alkaline or reducing conditions the solid remains largely undissolved and chemically persistent. Complexation of released copper ions by ligands (e.g., ammonia, sulfide, chloride) can shift equilibria toward soluble copper species.
Reactivity and Stability
Cu2S is chemically stable under anoxic, neutral to mildly reducing conditions but is susceptible to surface oxidation to higher sulphur/copper phases (e.g., CuS, CuO) and to desulfurization in high-temperature or strongly oxidizing environments. It reacts with strong mineral acids and oxidants, which can liberate soluble copper and sulfur species; mechanical processing (grinding) increases surface area and can accelerate oxidative dissolution. Thermal treatment produces phase transitions and may generate volatile sulfur species if decomposition proceeds under reducing conditions. Typical industrial concerns center on controlling oxidation, preventing dust formation, and managing aqueous releases of copper.
Molecular and Ionic Parameters
Formula and Molecular Weight
- Molecular formula: Cu2S
- Molecular weight: 159.16
- Exact mass: 157.831265
- Monoisotopic mass: 157.831265
These values reflect the stoichiometric binary composition of two copper atoms per sulfur atom and are useful for bulk-material calculations and analytical mass-balance.
Constituent Ions
- Constituent species: copper (nominally Cu(I)) and sulfide (S2−).
- Component compounds listed in source annotations: Sulfide ion and Copper.
Copper in Cu2S is formally in the +1 oxidation state, though electronic delocalization and non-stoichiometry can produce mixed-valence character in real materials.
Identifiers and Synonyms
Registry Numbers and Codes
- CAS number: 22205-45-4
- European Community (EC) Number: 244-842-9
- UNII: 349M3C1RS1
- ChEBI: CHEBI:51114
- InChI: InChI=1S/2Cu.S/q2*+1;-2
- InChIKey: AQMRBJNRFUQADD-UHFFFAOYSA-N
- SMILES: [S-2].[Cu+].[Cu+]
These identifiers are applicable for material specification, regulatory filings, and cheminformatics cross-referencing.
Synonyms and Common Names
- cuprous sulfide
- Cu2S cpd
- copper(I) sulfide
- CUPROUS SULFIDE
- Cuprasulfide
- Dicopper sulfide
- Dicopper monosulfide
- Copper sulfide (Cu2S)
- Kupfer(I)-sulfid
- Cuprous sulfide (Cu2S)
- Cu2S cpd
- (CUPRIOSULFANYL)COPPER
- copper(1+) sulfide
- copper(1+);sulfide
- copper sulfide (chalcocite)
- CUPROUS SULFIDE [MI]
- Dicopper sulphide
(A selection of depositor-supplied and MeSH synonyms as reported for the substance.)
Industrial and Commercial Applications
Functional Roles and Use Sectors
Copper(I) sulfide occurs naturally as the mineral chalcocite and is used in several industrial contexts based on its electronic, catalytic, and solid-state properties. Reported roles include use as a pigment or coating component in luminous paints, as electrode material in certain thermoelectric or electrochemical applications, in solid-lubricant formulations, and as a precursor or active component in heterogeneous catalysis. Production and handling are associated with primary metal manufacturing and mining sectors.
Typical Application Examples
- Occurrence as the mineral chalcocite and processing intermediate in copper metallurgy.
- Use in pigment and coating formulations where copper sulfide color and stability are required.
- Use in electrodes for thermoelements and in specialized electrical contacts.
- Use as a solid lubricant component and as a catalyst precursor in selected chemical processes.
If a concise application summary specific to a given material batch is required, practitioners should consult supplier technical data and product specifications.
Safety and Handling Overview
Health and Environmental Hazards
- Primary hazard notes: May cause irritation.
- Reported toxicology summary: Excess copper can be hepatotoxic by accumulation in liver tissues, inducing oxidative stress and inhibiting thiol-dependent enzymes; copper exposure can produce gastrointestinal and respiratory symptoms at elevated doses. Reported fatal dose for copper salts: 10 to 20 \(\mathrm{g}\) for an adult human.
- Acute exposure guidance: Acute oral minimal risk levels reported as \(0.01\,\mathrm{mg}\,\mathrm{kg}^{-1}\,\mathrm{day}^{-1}\) (listed in source annotations).
- Occupational exposure limits (as copper): MAK: \(0.01\,\mathrm{mg}\,\mathrm{m}^{-3}\) (respirable fraction, inorganic compounds); PEL: \(1.0\,\mathrm{mg}\,\mathrm{m}^{-3}\), as Cu; TLV: \(1.0\,\mathrm{mg}\,\mathrm{m}^{-3}\), as Cu; IDLH: \(100.0\,\mathrm{mg}\,\mathrm{m}^{-3}\), as Cu.
These values and hazard characterizations reflect copper-related exposure metrics and general sulfide particulate hazards; actual risk depends on particle size, surface oxidation state, and soluble copper release.
Storage and Handling Considerations
Handle copper sulfide as a dusty inorganic solid: minimize dust generation, provide local exhaust ventilation or dust capture, and use appropriate respiratory protection if airborne concentrations may exceed occupational limits. Use chemical-resistant gloves and eye protection to avoid mechanical irritation; contaminated clothing should be removed and laundered. Store in a dry, cool, well-ventilated area away from strong oxidizers and strong acids to limit oxidation and acid-driven release of sulfur species. For spill response, use methods appropriate for insoluble particulate solids (dampen to suppress dust, collect mechanically, and dispose of material in accordance with local regulations).
For detailed hazard, transport and regulatory information, users should refer to the product-specific Safety Data Sheet (SDS) and local legislation.
