Lead(II) oxide

{{chembox | Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 441024062 | ImageFile1 = Oxid olovnatý.JPG | ImageSize1 = 244 | ImageFile2 = PbO_structure.png | ImageSize2 = 180 | IUPACName = Lead(II) oxide | OtherNames = Lead monoxide Litharge Massicot Plumbous oxide | Section1 = {{Chembox Identifiers | CASNo = 1317-36-8 | CASNo_Ref = {{cascite|correct|CAS}} | ChemSpiderID = 140169 | ChEBI = 81045 | EC_number = 215-267-0 | KEGG = C17379 | PubChem = 14827 | UNNumber = 3288 2291 3077 | RTECS = OG1750000 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = 4IN6FN8492 | StdInChI=1S/O.Pb | StdInChIKey = YEXPOXQUZXUXJW-UHFFFAOYSA-N | SMILES = O=[Pb] }} | Section2 = {{Chembox Properties | Formula = PbO | MolarMass = 223.20 g/mol | Appearance = red or yellow powder | Density = 9.53 g/cm3 | MeltingPtC = 888 | BoilingPtC = 1477 | Solubility = α-PbO: 0.0504 g/L (25 °C) β-PbO: 0.1065 g/L (25 °C)<ref name=Greninger1977>{{cite book |author1=Dorothy Greninger |author2=Valerie Kollonitsch |author3=Charles Howard Kline |title=Lead Chemicals |publisher=International Lead Zinc Research Organization |year=1977 |url=https://books.google.com/books?id=pOQgAQAAIAAJ |page=52}}</ref> | SolubleOther = insoluble | MagSus = {{val|4.20|e=-5|u=cm3/mol}}}} | Section3 = {{Chembox Structure | Coordination = | CrystalStruct = Tetragonal, tP4 | SpaceGroup = P4/nmm, No. 129}} | Section7 = {{Chembox Hazards | ExternalSDS = [http://www.inchem.org/documents/icsc/icsc/eics0288.htm ICSC 0288] | GHSPictograms = {{GHS07}}{{GHS08}}{{GHS09}} | GHSSignalWord = Danger | HPhrases = {{H-phrases|302|332|351|360Df|362|373|410}} | PPhrases = {{P-phrases|201|202|260|261|263|264|270|271|273|281|301+312|304+312|304+340|308+313|312|314|330|391|405|501}} | NFPA-H = 3 | NFPA-F = 0 | NFPA-R = 0 | NFPA-S = | FlashPt = Non-flammable | LDLo = 1400 mg/kg (dog, oral)<ref name=IDLH>{{IDLH|7439921|Lead compounds (as Pb)}}</ref>}} | Section8 = {{Chembox Related | OtherAnions = Lead(II) sulfide Lead selenide Lead telluride | OtherCations = Germanium monoxide Tin(II) oxide | OtherFunction = Lead(II,IV) oxide Lead dioxide | OtherFunction_label = | OtherCompounds = Thallium(III) oxide Bismuth(III) oxide}}}}

'''Lead(II) oxide''', also called '''lead monoxide''', is the inorganic compound with the molecular formula Pb O. It is insoluble in water.<ref name=":2">{{Cite book |title=Dictionary of chemistry |date= |publisher=Oxford University Press |year=2020 |isbn=978-0-19-884122-7 |editor-last=Rennie |editor-first=Richard |edition=8th |series=Oxford quick reference |location=Oxford, United Kingdom; New York, NY |page=33}}</ref> It occurs in two polymorphs: litharge having a tetragonal crystal structure, and massicot having an orthorhombic crystal structure. Modern applications for PbO are mostly in lead-based industrial glass and industrial ceramics, including computer components.

== Types == Lead oxide exists in two polymorphs: * Red tetragonal (α-PbO), obtained at temperatures below {{Convert|486|C|F}} * Yellow orthorhombic (β-PbO), obtained at temperatures above {{Convert|486|C|F}}

==Synthesis== PbO may be prepared by heating lead metal in air at approximately {{convert|600|C|F|-2}}. At this temperature it is also the end product of decomposition of other oxides of lead in air:<ref name="G&E">{{Greenwood&Earnshaw2nd|pages=382-387}}</ref> :<chem>PbO2->[{293 °C}] Pb12O19 ->[{351 °C}] Pb12O17 ->[{375 °C}] Pb3O4 ->[{605 °C}] PbO</chem>

Thermal decomposition of lead(II) nitrate or lead(II) carbonate also results in the formation of PbO: :2 {{chem|Pb|(NO|3|)|2}} → 2 PbO + 4 {{chem|link=nitrogen dioxide|NO|2}} + {{chem|O|2}} :{{chem|PbCO|3}} → PbO + {{CO2|link=yes}}

PbO is produced on a large scale as an intermediate product in refining raw lead ores into metallic lead. The usual lead ore is galena (lead(II) sulfide). At a temperature of around {{convert|1000|C|F|-2}} in air, the sulfide converted to the oxide:<ref>{{cite journal|title=Thermal and XRD analysis of Egyptian galena|journal=Journal of Thermal Analysis and Calorimetry|year=2006|volume=86|issue=2|pages=393–401|last1=Abdel-Rehim|first1=A. M. |doi=10.1007/s10973-005-6785-6|s2cid=96393940}}</ref> :{{chem2|2 PbS + 3 O2 → 2 PbO + 2 SO2}}

=== From lead === Lead combusts at high temperature.<ref name=":0">{{Cite journal |last=Dix |first=J. E. |date=1987-02-01 |title=A comparison of barton-pot and ball-mill processes for making leady oxide |url=https://dx.doi.org/10.1016/0378-7753%2887%2980024-1 |journal=Journal of Power Sources |language=en |volume=19 |issue=2 |pages=157–161 |doi=10.1016/0378-7753(87)80024-1 |bibcode=1987JPS....19..157D |issn=0378-7753|url-access=subscription }}</ref> According to the Barton pot method, refined molten lead droplets are oxidized under a forced air flow which carries them out to the separation system (e.g. cyclonic separators) for further processing.<ref name=":0" /><ref name=":1">{{Cite book |last=Pavlov |first=D. |title=Lead-acid batteries : science and technology : a handbook of lead-acid battery technology and its influence on the product |date=2017 |isbn=978-0-444-59560-7 |edition=2 |location=Saint Louis |oclc=978538577}}</ref>{{Rp|page=245}} Oxides produced by this method are mostly a mixture of α-PbO and β-PbO. The overall reaction, which is conducted at 450 °C is: :{{chem2|Pb + O2 -> 2 PbO}} Using a Ball mill, lead balls are oxidized in a cooled rotating drum. The oxidation is achieved by collisions of the balls. Just like in Barton pot method, the supply of air and separators may also be used.<ref name=":0" />{{r|:1|p=245}}

==Structure== As determined by X-ray crystallography, both polymorphs, tetragonal and orthorhombic feature a pyramidal four-coordinate lead center. In the tetragonal form the four lead–oxygen bonds have the same length, but in the orthorhombic two are shorter and two longer. The pyramidal nature indicates the presence of a stereochemically active lone pair of electrons.<ref>{{Wells5th}}{{page needed|date=June 2017}}</ref> When PbO occurs in tetragonal lattice structure it is called litharge, and when the PbO has orthorhombic lattice structure it is called massicot.<ref name=":2" /> The PbO can be changed from massicot to litharge or vice versa by controlled heating and cooling.<ref>A simple example is given in {{cite book |author=Anil Kumar De |title=A Textbook Of Inorganic Chemistry |chapter-url=https://books.google.com/books?id=PpTi_JAx7PgC&pg=PA383 |year=2007 |publisher=New Age International |isbn=978-81-224-1384-7 |pages=383 |chapter=§9.2.6 Lead (Pb): Lead Monoxide PbO }} A more complex example is in {{cite book |first=N.Y. |last=Turova |title=The Chemistry of Metal Alkoxides |chapter-url=https://books.google.com/books?id=rPzaMRjK8pQC&pg=PA115 |date=2002 |publisher=Springer |isbn=978-0-7923-7521-0 |pages=115 |chapter=§9.4 Germanium, tin, lead alkoxides}}</ref> The tetragonal form is usually red or orange color, while the orthorhombic is usually yellow or orange, but the color is not a very reliable indicator of the structure.<ref>{{cite book |first=David John |last=Rowe |title=Lead Manufacturing in Britain: A History |url=https://books.google.com/books?id=ZL4OAAAAQAAJ&pg=PA16 |date=1983 |publisher=Croom Helm |isbn=978-0-7099-2250-6 |pages=16}}</ref> The tetragonal and orthorhombic forms of PbO occur naturally as rare minerals.

{{gallery|mode=packed-hover |title=Crystal structure in litharge form<ref name="G&E" /><ref>{{ cite journal | doi = 10.1016/S0167-2738(01)00699-3 | journal = Solid State Ion. | year = 2001 | volume = 140 | pages = 115–123 | first1 = Caroline | last1 = Pirovano | first2 = M. Saiful | last2 = Islam | authorlink2 = Saiful Islam (professor) | first3 = Rose-Noëlle | last3 = Vannier | first4 = Guy | last4 = Nowogrocki | first5 = Gaëtan | last5 = Mairesse | title = Modelling the crystal structures of Aurivillius phases | issue = 1–2 }}</ref><ref>{{ cite web | url = https://www.ccdc.cam.ac.uk/structures/Search?Ccdcid=1653774&DatabaseToSearch=Published | title = ICSD Entry: 94333 | author =  | website = Cambridge Structural Database: Access Structures | publisher = Cambridge Crystallographic Data Centre | access-date = 2021-06-01 }}</ref> |File:PbO-litharge-xtal-Pb-coordination-3D-bs-17.png|Pb coordinates square-pyramidally |File:PbO-litharge-xtal-O-coordination-3D-bs-17.png|O coordinates distorted-tetrahedrally |File:PbO-litharge-xtal-unit-cell-3D-bs-17.png|Unit cell |File:PbO-litharge-xtal-3x3x3-3D-bs-17.png|{{math|3×3×3}} unit cells |File:PbO-litharge-xtal-3x3x3-a-3D-bs-17.png|Along the {{mvar|a}} axis |File:PbO-litharge-xtal-3x3x3-c-3D-bs-17.png|Along the {{mvar|c}} axis }}

==Reactions== PbO is reduced to elemental lead when heated under carbon monoxide at around {{convert|1200|C|F|-2}}: :PbO + CO → Pb + {{CO2}}

The red and yellow forms of this material are related by a small change in enthalpy: :PbO(red) → PbO(yellow) {{pad|5em}} Δ''H'' = 1.6 kJ/mol

PbO is amphoteric,<ref name=":2" /> which means that it reacts with both acids and with bases. With acids, it forms salts of {{chem|Pb|2+}} via the intermediacy of oxo clusters such as {{chem|[Pb|6|O(OH)|6|]|4+}}. With strong bases, PbO dissolves to form plumbite (also called plumbate(II)) salts:<ref name=":2" /><ref name="Holl">{{Holleman&Wiberg}}{{page needed|date=June 2017}}</ref> :PbO + {{H2O}} + {{chem|OH|−}} → {{chem|[Pb(OH)|3|]|−}}

==Applications== PbO is used extensively in making glass. Depending on the glass formula, the effect of PbO can be one or more of: * increasing the refractive index, * increasing the dispersion (i. e. reducing the Abbe number), * decreasing the viscosity, * increasing the electrical resistivity, * increasing the absorption of X-ray radiation. Historically, PbO was used extensively in ceramic glazes for household ceramics. Technical ceramics also make use of PbO, including ferroelectric and piezoelectric materials, used in capacitors, actuators and electrooptic devices.<ref>{{cite book|editor-first1=James F.|editor-last1=Shackelford|editor-first2=Robert H.|editor-last2=Doremus|title=Ceramic and Glass Materials: Structure, Properties and Processing|publisher=Springer Science & Business Media|date=2008|page=159|url=https://books.google.com/books?id=ASIYuNCp81YC&pg=PA159|isbn=9780387733623|via=Google Books|access-date=2025-10-06}}</ref> Other less dominant applications include the vulcanization of rubber and the production of certain pigments and paints.<ref name=Ullmann>{{Ullmann|first=Dodd S.|last=Carr|year=2005|title=Lead Compounds|doi=10.1002/14356007.a15_249}}</ref> PbO is used in cathode-ray tube glass to block X-ray emission, but mainly in the neck and funnel of the tube, because it can cause discoloration when used in the faceplate. Strontium oxide and Barium oxide are preferred for the faceplate.<ref>{{Cite book|url=https://books.google.com/books?id=FvkqeL4IDMwC&q=lead+funnel&pg=PA9|title=Image Performance in CRT Displays|first=Kenneth|last=Compton|date=5 December 2003|publisher=SPIE Press|isbn=9780819441447|via=Google Books}}</ref>

The consumption of lead, and hence the processing of PbO, correlates with the number of automobiles, because lead remains the key component of automotive lead–acid batteries.<ref>{{Ullmann|first1=Charles A.|last1=Sutherland|first2=Edward F.|last2=Milner|first3=Robert C.|last3=Kerby|first4=Herbert|last4=Teindl|first5=Albert|last5=Melin|first6=Hermann M.|last6=Bolt|title=Lead|doi=10.1002/14356007.a15_193.pub2}}</ref>

===Niche or declining uses=== A mixture of PbO with glycerine sets to a hard, waterproof cement that has been used to join the flat glass sides and bottoms of aquariums, and was also once used to seal glass panels in window frames. It is a component of lead paints.

PbO was one of the raw materials for century eggs, a type of Chinese preserved egg. but it has been gradually replaced due to health problems. It was an unscrupulous practice in some small factories but it became rampant in China and forced many honest manufacturers to label their boxes "lead-free" after the scandal went mainstream in 2013.

In powdered tetragonal litharge form, it can be mixed with linseed oil and then boiled to create a weather-resistant sizing used in gilding. The litharge would give the sizing a dark red color that made the gold leaf appear warm and lustrous, while the linseed oil would impart adhesion and a flat durable binding surface.

PbO is used in certain condensation reactions in organic synthesis.<ref>{{OrgSynth| last=Corson |first=B. B. |year=1936 |title=1,4-Diphenylbutadiene |volume=16 |pages=28 |collvol=2 |collvolpages=229 |prep=CV2P0229}}</ref>

PbO is the input photoconductor in a video camera tube called the Plumbicon.

==Health issues== thumb|left {{Main|Lead poisoning}} Lead oxide is toxic and irritating to skin, eyes, and respiratory tract. It affects gum tissue, the central nervous system, the kidneys, the blood, and the reproductive system. It can bioaccumulate in plants and in mammals.<ref>{{cite web |url= http://www.ilo.org/safework_bookshelf/english?d&nd=857171610 |title= Lead(II) oxide |access-date= 2009-06-06 |publisher= International Occupational Safety and Health Information Centre |archive-url= https://web.archive.org/web/20111215095749/http://www.ilo.org/safework_bookshelf/english?d&nd=857171610 |archive-date= 2011-12-15 |url-status= dead }}</ref>

==References== {{Reflist}}

==External links== *[https://www.atsdr.cdc.gov/csem/csem.html Case Studies in Environmental Medicine - Lead Toxicity] {{Webarchive|url=https://web.archive.org/web/20160204174821/http://www.atsdr.cdc.gov/csem/csem.asp?csem=7&po=7 |date=2016-02-04 }} *[https://www.atsdr.cdc.gov/csem/csem.html ToxFAQs: Lead] {{Webarchive|url=https://web.archive.org/web/20160204174821/http://www.atsdr.cdc.gov/csem/csem.asp?csem=7&po=7 |date=2016-02-04 }} *[https://web.archive.org/web/20080111154608/http://www.npi.gov.au/database/substance-info/profiles/50.html National Pollutant Inventory - Lead and Lead Compounds Fact Sheet] *[http://www.webelements.com/compounds/lead/lead_oxide.html Webelements PbO]

Category:Amphoteric compounds Category:Lead(II) compounds Category:Oxides