Editing Calcium oxide (section)

{{Short description|Chemical compound of calcium}}
{{Redirect-distinguish|Quicklime|Quickline}}
{{Chembox
| Name           = Calcium oxide
| ImageFile      = Calcium-oxide-3D-vdW.png
| ImageSize      = 
| ImageName      = Calcium oxide
| ImageFile1     = Calcium oxide powder.JPG
| ImageCaption   = Ionic crystal structure of calcium oxide<br/>{{colorbox|#ffffff}} [[Calcium|Ca<sup>2+</sup>]] {{colorbox|#ff0000}} [[Oxygen|O]]<sup>[[Oxide|2-]]</sup>
| ImageCaption1  = Powder sample of white calcium oxide
| IUPACName      = Calcium oxide
| OtherNames     = {{Unbulleted list|[[Lime (material)|Lime]]|Quicklime|Burnt lime|Unslaked lime|Free lime ''(building)''|Caustic lime|Pebble lime|Calcia|Oxide of calcium}}
| SystematicName = 
| Section1       = {{Chembox Identifiers
| ChemSpiderID = 14095
| UNII = C7X2M0VVNH
| InChI = 1/Ca.O/rCaO/c1-2
| ChEBI = 31344
| ChEMBL = 2104397
| EC_number = 215-138-9
| InChIKey = ODINCKMPIJJUCX-BFMVISLHAU
| CASNo = 1305-78-8
| PubChem = 14778
| RTECS = EW3100000
| Gmelin = 485425
| KEGG = C13140
| UNNumber = 1910
| StdInChI=1S/Ca.O
| StdInChIKey = ODINCKMPIJJUCX-UHFFFAOYSA-N
| SMILES = O=[Ca] 
}}
| Section2       = {{Chembox Properties
| Formula = CaO
| MolarMass = 56.0774{{nbsp}}g/mol
| Appearance = White to pale yellow/brown powder
| Odor = Odorless
| Density = 3.34{{nbsp}}g/cm<sup>3</sup><ref name=crc/>
| Solubility = Reacts to form [[calcium hydroxide]]
| MeltingPtC = 2613
| MeltingPt_ref = <ref name=crc>{{RubberBible92nd|page=4.55}}</ref>
| BoilingPtC = 2850 
| BoilingPt_notes = (100{{nbsp}}[[hPa]])<ref name=r1>[http://gestis.itrust.de/nxt/gateway.dll/gestis_de/001200.xml?f=templates$fn=default.htm$3.0 Calciumoxid] ({{webarchive|url=https://web.archive.org/web/20131230232501/http://gestis.itrust.de/nxt/gateway.dll/gestis_de/001200.xml?f=templates%24fn%3Ddefault.htm%243.0 |date=2013-12-30 }}). GESTIS database</ref>
| pKa = 12.8
| Solvent2 = Methanol
| Solubility2 = Insoluble (also in [[diethyl ether]], [[octanol]])
| MagSus = −15.0×10<sup>−6</sup>{{nbsp}}cm<sup>3</sup>/mol
}}
| Section3       = {{Chembox Structure
| CrystalStruct = [[Cubic crystal system|Cubic]], [[Pearson symbol|cF8]]
}}
| Section4       = 
| Section5       = {{Chembox Thermochemistry
| DeltaHf = −635&nbsp;kJ·mol<sup>−1</sup><ref name=b1>{{cite book| author = Zumdahl, Steven S.|title =Chemical Principles 6th Ed.| publisher = Houghton Mifflin Company| year = 2009| isbn = 978-0-618-94690-7|page=A21}}</ref>
| Entropy = 40&nbsp;J·mol<sup>−1</sup>·K<sup>−1</sup><ref name=b1 />
 }}
| Section6       = {{Chembox Pharmacology
| ATCvet = yes
| ATCCode_prefix = P53
| ATCCode_suffix = AX18
}}
| Section7       = {{Chembox Hazards
| GHSPictograms = {{GHS05}}{{GHS07}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|302|314|315|335}}
| PPhrases = {{P-phrases|260|261|264|270|271|280|301+312|301+330+331|302+352|303+361+353|304+340|305+351+338|310|312|321|330|332+313|362|363|403+233|405|501}}
| ExternalSDS = [https://www.inchem.org/documents/icsc/icsc/eics0409.htm ICSC 0409]
| NFPA-H = 3
| NFPA-F = 0
| NFPA-R = 2
| NFPA-S = w
| FlashPt = Non-flammable
| FlashPt_ref = <ref name=PGCH/>
| PEL = TWA 5{{nbsp}}mg/m<sup>3</sup><ref name=PGCH>{{PGCH|0093}}</ref>
| REL = TWA 2{{nbsp}}mg/m<sup>3</sup><ref name=PGCH/>
| IDLH = 25{{nbsp}}mg/m<sup>3</sup><ref name=PGCH/>
| LD50 = >2000 mg/kg oral, female rat <ref>https://www.fishersci.com/store/msds?partNumber=AC196910025&countryCode=US&language=en</ref>
}}
| Section8       = {{Chembox Related
| OtherAnions = {{Plainlist|
* [[Calcium sulfide]]
* [[Calcium hydroxide]]
* [[Calcium selenide]]
* [[Calcium telluride]]
}}
| OtherCations = {{Plainlist|
* [[Beryllium oxide]]
* [[Magnesium oxide]]
* [[Strontium oxide]]
* [[Barium oxide]]
* [[Radium oxide]]
}}
}}
}}

'''Calcium oxide''' ([[chemical formula|formula]]: [[calcium|Ca]][[oxygen|O]]), commonly known as '''quicklime''' or '''burnt lime''', is a widely used [[chemical compound]]. It is a white, [[corrosive substance|caustic]], [[alkali]]ne, [[crystal]]line solid at [[room temperature]]. The broadly used term ''[[lime (material)|lime]]'' connotes calcium-containing [[inorganic compound]]s, in which [[carbonate]]s, [[oxide]]s, and [[hydroxide]]s of calcium, [[silicon]], [[magnesium]], [[aluminium]], and [[iron]] predominate. By contrast, ''quicklime'' specifically applies to the single compound calcium oxide. Calcium oxide that survives processing without reacting in [[building material|building products]], such as [[cement]], is called '''free lime'''.<ref>{{cite web |url=http://www.dictionaryofconstruction.com/definition/free-lime.html |title=free lime |publisher= DictionaryOfConstruction.com |archive-url=https://web.archive.org/web/20171209222951/http://www.dictionaryofconstruction.com/definition/free-lime.html |archive-date=2017-12-09 |url-status=dead}}</ref>

Quicklime is relatively inexpensive. Both it and the chemical derivative [[calcium hydroxide]] (of which quicklime is the [[base anhydride]]) are important commodity chemicals.