Editing Barium oxide

{{Short description|Chemical compound used in cathode-ray tubes}}
{{redirect|BaO||BAO (disambiguation)|and|Bao (disambiguation)}}
{{Chembox
| Verifiedfields = changed
| Watchedfields  = changed
| verifiedrevid  = 443645196
| Name           = Barium oxide
| ImageFile      = Barium-oxide-3D-vdW.png
| ImageFile1     = Barium oxide.JPG
| OtherNames     = {{unbulleted list
| Neutral barium oxide (1:1)
| Barium protoxide
| Calcined baryta
| Baria }}
| IUPACName = 
| SystematicName = 
| Section1 = {{Chembox Identifiers
 | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
 | ChemSpiderID = 56180
 | InChI        = 1/Ba.O/rBaO/c1-2
 | SMILES       = [Ba]=O
 | InChIKey     = QVQLCTNNEUAWMS-FXUTYLCTAB
 | StdInChI_Ref    = {{stdinchicite|correct|chemspider}}
 | StdInChI        = 1S/Ba.O
 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
 | StdInChIKey     = QVQLCTNNEUAWMS-UHFFFAOYSA-N
 | CASNo     = 1304-28-5
 | CASNo_Ref = {{cascite|correct|CAS}}
 | UNII_Ref  = {{fdacite|correct|FDA}}
 | UNII    = 77603K202B
 | RTECS   = CQ9800000
 | PubChem = 62392
 | EC_number = 215-127-9
 | UNNumber  = 1884
}}
| Section2 = {{Chembox Properties
 | Formula = 
 | Ba=1 | O   = 1
 | MolarMass  = 153.326 g/mol
 | Appearance = white solid
 | Density    = 5.72 g/cm<sup>3</sup>, solid
 | Solubility = {{unbulleted list
 | 3.48 g/100 mL (20 °C)
 | 90.8 g/100 mL (100 °C)
 | Reacts to form [[Barium hydroxide|Ba(OH)<sub>2</sub>]] }}
 | SolubleOther = soluble in [[ethanol]], dilute mineral acids and alkalies; insoluble in [[acetone]] and liquid [[ammonia]]
 | MeltingPtC   = 1923
 | MeltingPt_notes = 
 | BoilingPt  = ~
 | BoilingPtC = 2000
 | MagSus     = −29.1·10<sup>−6</sup> cm<sup>3</sup>/mol
}}
| Section3 = {{Chembox Structure
 | Coordination  = [[octahedron|Octahedral]]
 | CrystalStruct = [[Cubic crystal system|cubic]], [[Pearson symbol|cF8]]
 | SpaceGroup    = Fm<u style="text-decoration:overline">3</u>m, No. 225
}}
| Section4 = {{Chembox Thermochemistry
 | DeltaHf      = −582&nbsp;kJ·mol<sup>−1</sup><ref name="Zumdahl">{{cite book| author = Zumdahl, Steven S.|title =Chemical Principles 6th Ed.| publisher = Houghton Mifflin Company| year = 2009| isbn = 978-0-618-94690-7}}</ref>
 | Entropy      = 70&nbsp;J·mol<sup>−1</sup>·K<sup>−1</sup><ref name="Zumdahl"/>
 | HeatCapacity = 47.7 J/K mol
}}
| Section5 = 
| Section6 = 
| Section7 = {{Chembox Hazards
 | GHSPictograms = {{GHS05}}{{GHS06}}{{GHS07}}
 | GHSSignalWord = Danger
 | HPhrases = {{H-phrases|301|302|314|315|332|412}}
 | PPhrases = {{P-phrases|210|220|221|260|261|264|270|271|273|280|283|301+310|301+312|301+330+331|302+352|303+361+353|304+312|304+340|305+351+338|306+360|310|312|321|330|332+313|362|363|370+378|371+380+375|405|501}}
 | NFPA-H   = 3
 | NFPA-F   = 0
 | NFPA-R   = 0
 | FlashPt  = Non-flammable
}}
| Section8 = {{Chembox Related
 | OtherAnions = {{unbulleted list
 | [[Barium hydroxide]]
 | [[Barium peroxide]] }}
 | OtherCations = {{unbulleted list
 | [[Beryllium oxide]]
 | [[Magnesium oxide]]
 | [[Calcium oxide]]
 | [[Strontium oxide]] }}
}}
}}

'''Barium oxide''', also known as '''baria''', is a white [[hygroscopic]] non-flammable [[chemical compound|compound]] with the formula BaO. It has a [[Cubic crystal system|cubic]] structure and is used in [[cathode-ray tube]]s, crown glass, and [[Catalysis|catalysts]]. It is harmful to human skin and if swallowed in large quantity causes irritation. Excessive quantities of barium oxide may lead to death.

It is prepared by heating [[barium carbonate]] with [[coke (fuel)|coke]], [[carbon black]] or [[tar]] or by [[thermal decomposition]] of [[barium nitrate]].{{Citation needed|date=September 2014}}

==Uses==
Barium oxide is used as a coating for [[hot cathode]]s, for example, those in [[cathode-ray tube]]s. It replaced [[lead(II) oxide]] in the production of certain kinds of glass such as optical [[crown glass (optics)|crown glass]]. While lead oxide raised the [[refractive index]], it also raised the [[optical dispersion|dispersive]] power, which barium oxide does not alter.<ref>{{cite encyclopedia  | title = Barium Oxide (chemical compound)  | encyclopedia = Encyclopædia Britannica  | year = 2007  | url = http://www.britannica.com/eb/topic-53368/barium-oxide  | access-date = 2007-02-19 }}</ref> Barium oxide also has use as an [[ethoxylation]] [[catalyst]] in the reaction of [[ethylene oxide]] and [[Alcohol (chemistry)|alcohol]]s, which takes place between 150 and 200&nbsp;°C.<ref>{{Cite web  | last1 = Nield  | first1 = Gerald  | last2 = Washecheck  | first2 = Paul  | last3 = Yang  | first3 = Kang  | title = United States Patent 4210764  | date = 1980-07-01  | url = http://www.freepatentsonline.com/4210764.html  | access-date = 2007-02-20 }}</ref>

It is most known for its use in the [[Brin process]], named after its inventors, a reaction that was used as a large scale method to produce oxygen before [[air separation]] became the dominant method in the beginning of the 20th century, as BaO can be a source of pure oxygen through heat fluctuation.

BaO(s) + ½O<sub>2</sub>(g) ⇌ BaO<sub>2</sub>(s)

It oxidises to BaO<sub>2</sub> by formation of a [[peroxide]] [[ion]] ({{Chem2|[O\sO](2–)}}, or {{chem2|O2(2–)}}) — with the same charge of {{Chem2|O(2–)}}, and therefore keeping the electrochemical balance with the most stable {{Chem2|Ba(2+)}}. Using the [[Kröger–Vink notation|Kröger-Vink notation]], 

½{{Chem2|O2}}(g) + O{{Su|b=O|p=2–}} ⇌ [O{{Su|b=2|p=}}]{{Su|b=O|p=2–}}

where J{{Su|b=O}} is the species J in the oxygen position within the rock-salt lattice. The complete peroxidation of BaO to BaO<sub>2</sub> occurs at moderate temperatures by oxygen uptake within the BaO rock-salt lattice:
[[File:Oxygen incorporation into BaO.png|border|left|thumb|246x246px|Barium oxide peroxidation from oxygen uptake, adapted from Middleburgh et al, 2012.<ref name=":0">{{Cite journal |last=Middleburgh |first=Simon C. |last2=Lagerlof |first2=Karl Peter D. |last3=Grimes |first3=Robin W. |date=2013 |title=Accommodation of Excess Oxygen in Group II Monoxides |url=https://ceramics.onlinelibrary.wiley.com/doi/abs/10.1111/j.1551-2916.2012.05452.x |journal=Journal of the American Ceramic Society |language=en |volume=96 |issue=1 |pages=308–311 |doi=10.1111/j.1551-2916.2012.05452.x |issn=1551-2916|url-access=subscription }}</ref>]]

Calculations using [[Density functional theory|Density Functional Theory (DFT)]] suggest that the oxygen incorporation reaction is exothermic, and that the most energetically favoured occupation site is indeed the peroxide ion at the oxide lattice — other than interstitial positions, for instance. However, the increased entropy of the system is what leads BaO<sub>2</sub> to decompose to BaO and release O<sub>2</sub> between 800 and 1100 K (520 and 820 °C).<ref name=":0" /> The reaction was used as a large scale method to produce oxygen before [[air separation]] became the dominant method in the beginning of the 20th century. The method was named the [[Brin process]], after its inventors.<ref>{{cite journal|author1-link=William B. Jensen | last1 = Jensen | first1 = William B. | title = The Origin of the Brin Process for the Manufacture of Oxygen | journal = Journal of Chemical Education | volume = 86 | pages = 1266 | year = 2009 | doi = 10.1021/ed086p1266 | issue = 11 |bibcode = 2009JChEd..86.1266J }}</ref>

==Preparation==
Barium oxide from metallic barium readily forms from its exothermic oxidation with [[dioxygen]] in air:

2 Ba(s) + O<sub>2</sub>(g) → 2 BaO(s).

It's most commonly made by heating [[barium carbonate]] at temperatures of 1000&ndash;1450 °C.

BaCO<sub>3</sub>(s) → BaO(s) + CO<sub>2</sub>(g)

Likewise, it is often formed through the thermal decomposition of other [[barium compounds|barium salts]],<ref>{{cite web  | title = Compounds of barium: barium (II) oxide  | work = Web Elements  | publisher = The University of Sheffield  | date = 2007-01-26  | url = http://www.webelements.com/webelements/compounds/text/Ba/Ba1O1-1304285.html  | access-date = 2007-02-22 }}</ref> like [[barium nitrate]].<ref>Pradyot Patnaik. ''Handbook of Inorganic Chemicals''. McGraw-Hill, 2002, {{ISBN|0-07-049439-8}}</ref>

==Safety issues==
Barium oxide is an [[irritation|irritant]]. If it contacts the skin or the eyes or is inhaled it causes pain and redness. However, it is more dangerous when ingested. It can cause [[nausea]] and [[diarrhea]], [[paralysis|muscle paralysis]], cardiac arrhythmia, and can cause death. If ingested, medical attention should be sought immediately.

Barium oxide should not be released environmentally; it is harmful to [[Marine biology|aquatic organisms]].<ref>{{cite web  | title = Barium Oxide (ICSC)  | publisher = IPCS  | date = October 1999  | url = http://www.inchem.org/documents/icsc/icsc/eics0778.htm  | access-date = 2007-02-19 | archive-url= https://web.archive.org/web/20070226194744/http://www.inchem.org/documents/icsc/icsc/eics0778.htm| archive-date= 26 February 2007 | url-status= live}}</ref>

==See also==
* {{annotated link|Barium}}

==References==
<references/>

==External links==
*[http://www.inchem.org/documents/icsc/icsc/eics0778.htm International Chemical Safety Card 0778]

{{Barium compounds}}
{{Oxides}}
{{Authority control}}
{{oxygen compounds}}

[[Category:Barium compounds]]
[[Category:Oxides]]
[[Category:Rock salt crystal structure]]