Editing Copper(II) oxide

{{Short description|Chemical compound – an oxide of copper with formula CuO}}
{{chembox
| Verifiedfields = changed
| verifiedrevid  = 476999309
| ImageFile      = copperIIoxide.jpg
| ImageSize      = 
| ImageFile1     = Copper(II)-oxide-unit-cell-3D-balls.png
| ImageSize1     = 
| ImageFile2     = Copper(II)-oxide-3D-balls.png
| ImageSize2     = 
| IUPACName      = Copper(II) oxide
| OtherNames     = Cupric oxide
| Section1       = {{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 144499
| ChEBI_Ref = {{ebicite|changed|EBI}}
| ChEBI = 75955
| ChEMBL_Ref = {{ebicite|changed|EBI}}
| ChEMBL = 1909057
| SMILES = [Cu]=O
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = V1XJQ704R4
| InChIKey = QPLDLSVMHZLSFG-PHEGLCPBAN
| InChI1 = 1/Cu.O/q+2;-2
| InChIKey1 = KKCXRELNMOYFLS-UHFFFAOYAT
| SMILES1 = [Cu+2].[O-2]
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/Cu.O/q+2;-2
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = KKCXRELNMOYFLS-UHFFFAOYSA-N
| CASNo = 1317-38-0
| CASNo_Ref = {{cascite|correct|CAS}}
| EC_number = 215-269-1
| PubChem = 14829
| InChI = 1/Cu.O/rCuO/c1-2
| RTECS = GL7900000
}}
| Section2       = {{Chembox Properties
| Formula = CuO
| MolarMass = 79.545 g/mol
| Appearance = black to brown powder
| Density = 6.315 g/cm<sup>3</sup>
| MeltingPtC = 1326
| BoilingPtC = 2000
| Solubility = insoluble
| SolubleOther = soluble in [[ammonium chloride]], [[potassium cyanide]] <br> insoluble in [[ethanol|alcohol]], [[ammonium carbonate]] 
| BandGap = 1.2&nbsp;[[Electronvolt|eV]]
| pKa = 
| pKb = 
| RefractIndex = 2.63
| MagSus = +238.9·10<sup>−6</sup> cm<sup>3</sup>/mol
}}
| Section3       = {{Chembox Structure
| CrystalStruct = [[monoclinic]], [[Pearson symbol|mS8]]<ref name= "Hull">The effect of hydrostatic pressure on the ambient temperature structure of CuO, Forsyth J.B., Hull S., J. Phys.: Condens. Matter 3 (1991) 5257–5261, {{doi|10.1088/0953-8984/3/28/001}}.  [[Crystallographic point group]]: 2/m or ''C<sub>2h</sub>''. [[Space group]]: C2/c.  Lattice parameters: ''a'' = 4.6837(5), ''b'' = 3.4226(5), ''c'' = 5.1288(6), ''α'' = 90°, ''β'' = 99.54(1)°, ''γ'' = 90°.</ref>
| SpaceGroup = C2/c, #15
| LattConst_a = 4.6837
| LattConst_b = 3.4226
| LattConst_c = 5.1288
| LattConst_beta = 99.54
| Coordination = 
}}
| Section4       = {{Chembox Thermochemistry
| DeltaHf = −156&nbsp;kJ·mol<sup>−1</sup>
| Entropy = 43&nbsp;J·mol<sup>−1</sup>·K<sup>−1</sup>
 }}
| Section7       = {{Chembox Hazards
| ExternalSDS = [https://fscimage.fishersci.com/msds/05655.htm Fisher Scientific]
| GHSPictograms = {{GHS07}}{{GHS09}}
| GHSSignalWord = Warning
| HPhrases = {{H-phrases|302|410|412}}
| PPhrases = {{P-phrases|P264|P270|P273|P301+P317|P330|P391|P501}}
| MainHazards = 
| NFPA-H = 2
| NFPA-F = 0
| NFPA-R = 1
| NFPA-S = 
| FlashPt = Non-flammable
| PEL = TWA 1 mg/m<sup>3</sup> (as Cu)<ref name=PGCH>{{PGCH|0150}}</ref>
| REL = TWA 1 mg/m<sup>3</sup> (as Cu)<ref name=PGCH/>
| IDLH =  TWA 100 mg/m<sup>3</sup> (as Cu)<ref name=PGCH/>
}}
| Section8       = {{Chembox Related
| OtherAnions = [[Copper(II) sulfide]]
| OtherCations = [[Nickel(II) oxide]]<br/>[[Zinc oxide]]
| OtherFunction = 
| OtherFunction_label = 
| OtherCompounds = [[Copper(I) oxide]]
}}
}}

'''Copper(II) oxide''' or '''cupric oxide''' is an [[inorganic compound]] with the formula CuO.  A black solid, it is one of the two stable [[oxide]]s of [[copper]], the other being Cu<sub>2</sub>O or [[copper(I) oxide]] (cuprous oxide).  As a [[mineral]], it is known as [[tenorite]], or sometimes black copper.  It is a product of [[Copper extraction|copper mining]] and the precursor to many other copper-containing products and chemical compounds.<ref name=Ullmann>{{Ullmann|first1=H. Wayne|last1=Richardson |title=Copper Compounds|year=2002|doi=10.1002/14356007.a07_567}}</ref>

==Production==
It is produced on a large scale by [[pyrometallurgy]], as one stage in extracting copper from its ores. The ores are treated with an aqueous mixture of [[ammonium carbonate]], [[ammonia]], and [[oxygen]] to ultimately give copper(II) [[ammine complex]] carbonates, such as {{chem2|[Cu(NH3)4]CO3}}. After extraction from the residues and after separation from iron, lead, etc. impurities, the carbonate salt is decomposed with steam to give CuO.<ref name=Ullmann/>  

It can be formed by heating copper in air at around 300–800&nbsp;°C:
: {{chem2|2 Cu + O2 → 2 CuO}}
For laboratory uses, copper(II) oxide is conveniently prepared by pyrolysis of [[copper(II) nitrate]] or [[basic copper(II) carbonate]]:<ref name=Brauer>{{cite book|author=O. Glemser and H. Sauer |chapter=Copper, Silver, Gold|title=Handbook of Preparative Inorganic Chemistry, 2nd Ed. |editor=G. Brauer|publisher=Academic Press|year=1963|place=NY, NY|volume=1}}</ref>  
: {{chem2|2 Cu(NO3)2 → 2 CuO  + 4 NO2  + O2}}  (180°C)
: {{chem2|Cu2(OH)2CO3 → 2 CuO + CO2 + H2O}}
Dehydration of cupric hydroxide has also been demonstrated:
:{{chem2|Cu(OH)2 → CuO + H2O}}

==Reactions==
Copper(II) oxide reacts with [[mineral acid]]s such as [[hydrochloric acid]], [[sulfuric acid]], and [[nitric acid]] to give the corresponding hydrated copper(II) salts:<ref name=Brauer/>
: CuO + 2 HNO<sub>3</sub> → Cu(NO<sub>3</sub>)<sub>2</sub> + H<sub>2</sub>O
: CuO + 2 HCl → CuCl<sub>2</sub> + H<sub>2</sub>O
: CuO + H<sub>2</sub>SO<sub>4</sub> → CuSO<sub>4</sub> + H<sub>2</sub>O

In presence of water it reacts with concentrated [[alkali]] to form the corresponding [[cuprate]] salts:
: 2 NaOH + CuO + H<sub>2</sub>O → Na<sub>2</sub>[Cu(OH)<sub>4</sub>]

It can also be reduced to [[copper]] metal using [[hydrogen]], [[carbon monoxide]], and [[carbon]]:
: CuO + H<sub>2</sub>   →   Cu + H<sub>2</sub>O
: CuO + CO   →   Cu + CO<sub>2</sub>
: 2 CuO + C   →   2Cu + CO<sub>2</sub>
When cupric oxide is substituted for iron oxide in [[thermite]] the resulting mixture is a low explosive, not an incendiary.

==Structure and physical properties==
Copper(II) oxide belongs to the [[monoclinic crystal system]]. The copper atom is coordinated by 4 oxygen atoms in an approximately square planar configuration.<ref name= "Hull"/>

The [[work function]] of bulk CuO is 5.3 [[Electronvolt|eV]].<ref>{{cite journal|journal=J. Appl. Phys.|volume=53|page=1173|year=1982|doi=10.1063/1.330567|author=F. P. Koffyberg and F. A. Benko|title=A photoelectrochemical determination of the position of the conduction and valence band edges of p-type CuO|issue=2|bibcode=1982JAP....53.1173K}}</ref>

==Uses==
As a significant product of copper mining, copper(II) oxide is the starting point for the production of many other copper salts. For example, many [[wood preservative]]s are produced from copper oxide.<ref name=Ullmann/>

Cupric oxide is used as a [[pigment]] in ceramics to produce blue, red, and green, and sometimes gray, pink, or black glazes.<ref name=Ullmann/>

It is incorrectly used as a dietary supplement in [[animal feed]].<ref>{{cite web|title = Uses of Copper Compounds: Other Copper Compounds|publisher = Copper Development Association|year = 2007|url = http://www.copper.org/applications/compounds/other_compounds.html|access-date = 2007-01-27|archive-date = 2013-08-15|archive-url = https://web.archive.org/web/20130815084358/http://www.copper.org/applications/compounds/other_compounds.html|url-status = dead}}</ref> Due to low bioactivity, negligible copper is absorbed.<ref name= "Baker">{{cite journal|doi=10.1093/jn/129.12.2278 |title=Cupric Oxide Should Not be Used as a Copper Supplement for Either Animals or Humans |date=1999 |last1=Baker |first1=David H. |journal=The Journal of Nutrition |volume=129 |issue=12 |pages=2278–2279 |pmid=10573563 }}</ref>

It is used when welding with [[copper alloys]].<ref>{{cite web|title = Cupric Oxide Data Sheet|publisher = Hummel Croton Inc.|date = 2006-04-21|url = http://www.axxousa.com/data/cuox_d.html|access-date = 2007-02-01|archive-date = 2011-07-07|archive-url = https://web.archive.org/web/20110707202129/http://www.axxousa.com/data/cuox_d.html|url-status = dead}}</ref>

A copper oxide electrode formed part of the early battery type known as the [[Edison–Lalande cell]]. Copper oxide was also used in a [[lithium battery]] type ([[IEC 60086]] code "G").

===Pyrotechnics and fireworks===
Used as moderate blue coloring agent in blue flame compositions with additional chlorine donors and oxidizers such as chlorates and perchlorates. Providing oxygen it can be used as flash powder oxidizer with metal fuels such as magnesium, aluminium, or magnalium powder. Sometimes it is used in strobe effects and thermite compositions as crackling stars effect.

==Similar compounds==
An example of [[Native copper|natural copper]](I,II) oxide is the mineral [[paramelaconite]], Cu<sup>+</sup><sub>2</sub>Cu<sup>2+</sup><sub>2</sub>O<sub>3</sub>.<ref name=Mindat>{{Cite web|url=https://www.mindat.org/min-3098.html|title=Paramelaconite}}</ref><ref name=IMA>{{Cite web|url=https://www.ima-mineralogy.org/Minlist.htm|title=List of Minerals|date=21 March 2011}}</ref>

==See also==
* [[Patina]]
* [[Tenorite]]

==References==
{{reflist|30em}}

==External links==
{{Commons category|Copper(II) oxide}}
*[https://web.archive.org/web/20080302034606/http://www.npi.gov.au/database/substance-info/profiles/27.html National Pollutant Inventory - Copper and compounds fact sheet]
* [http://copperoxides.altervista.org/ Copper oxides project page] {{Webarchive|url=https://web.archive.org/web/20110725001301/http://copperoxides.altervista.org/ |date=2011-07-25 }}
*[https://www.cdc.gov/niosh/npg/npgd0151.html CDC - NIOSH Pocket Guide to Chemical Hazards]

{{Copper compounds}}
{{Oxides}}
{{Oxygen compounds}}

[[Category:Copper(II) compounds]]
[[Category:Semiconductor materials]]
[[Category:Pyrotechnic colorants]]
[[Category:Transition metal oxides]]
[[Category:Glass dyes]]