Cuprous oxide

Copper(I) oxide

Names
IUPAC name Copper(I) oxide
Other names Cuprous oxide Dicopper oxide Cuprite Red copper oxide
Identifiers
CAS Number	1317-39-1 Y
3D model (Jmol)	Interactive image Interactive image
ChemSpider	8488659 Y
ECHA InfoCard	100.013.883
EC Number	215-270-7
KEGG	C18714 Y
PubChem CID	10313194
RTECS number	GL8050000
UNII	T8BEA5064F Y
InChI InChI=1S/2Cu.O/q2*+1;-2 Y Key: KRFJLUBVMFXRPN-UHFFFAOYSA-N Y InChI=1/2Cu.O/rCu2O/c1-3-2 Key: BERDEBHAJNAUOM-YQWGQOGZAF InChI=1/2Cu.O/q2*+1;-2 Key: KRFJLUBVMFXRPN-UHFFFAOYAM
SMILES [Cu]O[Cu] [Cu+].[Cu+].[O-2]
Properties
Chemical formula	Cu2O
Molar mass	143.09 g/mol
Appearance	brownish-red solid
Density	6.0 g/cm3
Melting point	1,232 °C (2,250 °F; 1,505 K)
Boiling point	1,800 °C (3,270 °F; 2,070 K)
Solubility in water	Insoluble
Solubility in acid	Soluble
Band gap	2.137 eV
Magnetic susceptibility (χ)	-20·10−6 cm3/mol
Structure
Crystal structure	cubic
Thermochemistry
Std molar entropy (So298)	93 J·mol−1·K−1
Std enthalpy of formation (ΔfHo298)	−170 kJ·mol−1
Hazards
Safety data sheet	SIRI.org
EU classification (DSD)	Harmful (Xn) Dangerous for the environment (N)
R-phrases	R22, R50/53
S-phrases	(S2), S22, S60, S61
NFPA 704	0 2 1
US health exposure limits (NIOSH):
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)
Related compounds
Other anions	Copper(I) sulfide Copper(II) sulfide Copper(I) selenide
Other cations	Copper(II) oxide Silver(I) oxide Nickel(II) oxide Zinc oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Copper(I) oxide or cuprous oxide is the inorganic compound with the formula Cu₂O. It is one of the principal oxides of copper, the other being CuO or cupric oxide. This red-coloured solid is a component of some antifouling paints. The compound can appear either yellow or red, depending on the size of the particles. Copper(I) oxide is found as the reddish mineral cuprite.

Copper(I) oxide may be produced by several methods. Most straightforwardly, it arises via the oxidation of copper metal:

Additives such as water and acids affect the rate of this process as well as the further oxidation to copper(II) oxides. It is also produced commercially by reduction of copper(II) solutions with sulfur dioxide. Aqueous cuprous chloride solutions react with base to give the same material. In all cases, the color is highly sensitive to the procedural details.

Formation of copper(I) oxide is the basis of the Fehling's test and Benedict's test for reducing sugars. These sugars reduce an alkaline solution of a copper(II) salt, giving a bright red precipitate of Cu₂O.

It forms on silver-plated copper parts exposed to moisture when the silver layer is porous or damaged. This kind of corrosion is known as red plague.

Little evidence exists for cuprous hydroxide, which is expected to rapidly undergo dehydration. A similar situation applies to the hydroxides of gold(I) and silver(I).

The solid is diamagnetic. In terms of their coordination spheres, copper centres are 2-coordinated and the oxides are tetrahedral. The structure thus resembles in some sense the main polymorphs of SiO₂, and both structures feature interpenetrated lattices.