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Lead(II) oxide
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<h2 id="types">Types</h2> <p>Lead oxide exists in two <a href="/facts/Polymorphism_(materials_science)/bu2tqsB9">polymorphs</a>: </p> <ul><li>Red tetragonal (α-PbO), obtained at temperatures below 486 °C (907 °F)</li> <li>Yellow orthorhombic (β-PbO), obtained at temperatures above 486 °C (907 °F)</li></ul> <h2 id="synthesis">Synthesis</h2> <p>PbO may be prepared by heating lead metal in air at approximately 600 °C (1,100 °F). At this temperature it is also the end product of decomposition of other <a href="/facts/Lead_oxide_(disambiguation)/NT1AxDpu">oxides of lead</a> in air:<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> </p> PbO 2 → 293 ° C Pb 12 O 19 → 351 ° C Pb 12 O 17 → 375 ° C Pb 3 O 4 → 605 ° C PbO {\displaystyle {\ce {PbO2->[{293 °C}] Pb12O19 ->[{351 °C}] Pb12O17 ->[{375 °C}] Pb3O4 ->[{605 °C}] PbO}}} <p>Thermal decomposition of <a href="/facts/Lead(II)_nitrate/k2494KxQ">lead(II) nitrate</a> or <a href="/facts/Lead_carbonate/KXw6ux0H">lead(II) carbonate</a> also results in the formation of PbO: </p> 2 Pb(NO3)2 → 2 PbO + 4 <a href="/facts/Nitrogen_dioxide/FoLvApPI">NO2</a> + O2 PbCO3 → PbO + <a href="/facts/Carbon_dioxide/xGzpppEp">CO2</a> <p>PbO is produced on a large scale as an intermediate product in refining raw lead ores into metallic lead. The usual lead ore is <a href="/facts/Galena/eSaK62FA">galena</a> (<a href="/facts/Lead(II)_sulfide/IXauvWYq">lead(II) sulfide</a>). At a temperature of around 1,000 °C (1,800 °F) in air, the sulfide converted to the oxide:<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> </p> 2 PbS + 2 O2 → 2 PbO + 2 SO2 <h3>From lead</h3> <p>Lead combusts at high temperature.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> 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. <a href="/facts/Cyclonic_separation/CrWt47Yy">cyclonic separators</a>) for further processing.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a><a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a>: 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: </p> Pb + O2 → 2 PbO <p>Using a <a href="/facts/Ball_mill/40Xn4KUQ">Ball mill</a>, 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.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a><a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a>: 245 </p> <h2 id="structure">Structure</h2> <p>As determined by <a href="/facts/X-ray_crystallography/WtI0F5DN">X-ray crystallography</a>, both polymorphs, <a href="/facts/Tetragonal/12Aop255">tetragonal</a> and <a href="/facts/Orthorhombic/3zo4F8P0">orthorhombic</a> 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 <a href="/facts/Stereochemistry/XkcRVNwd">stereochemically</a> active <a href="/facts/Lone_pair/Q6kEAC4g">lone pair</a> of electrons.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> When PbO occurs in tetragonal lattice structure it is called <a href="/facts/Litharge/qCyjHJ83">litharge</a>; and when the PbO has orthorhombic lattice structure it is called <a href="/facts/Massicot/U5rgRMeu">massicot</a>. The PbO can be changed from massicot to litharge or vice versa by controlled heating and cooling.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> 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.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> The tetragonal and orthorhombic <a href="/facts/Polymorphism_(materials_science)/bu2tqsB9">forms</a> of PbO occur naturally as rare minerals. </p> Crystal structure in litharge form<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a><a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a><a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> <h2 id="reactions">Reactions</h2> <p>PbO is reduced to elemental lead when heated under <a href="/facts/Carbon_monoxide/CKuLtEMJ">carbon monoxide</a> at around 1,200 °C (2,200 °F): </p> PbO + CO → Pb + CO2 <p>The red and yellow forms of this material are related by a small change in <a href="/facts/Enthalpy/bBou8lCE">enthalpy</a>: </p> PbO(red) → PbO(yellow) Δ<i>H</i> = 1.6 kJ/mol <p>PbO is <a href="/facts/Amphoterism/2UrXEsyl">amphoteric</a>, which means that it reacts with both acids and with bases. With acids, it forms salts of Pb2+ via the intermediacy of oxo <a href="/facts/Cluster_chemistry/EsuLgxJU">clusters</a> such as [Pb6O(OH)6]4+. With strong bases, PbO dissolves to form <a href="/facts/Plumbite/MmWkNwkc">plumbite</a> (also called plumbate(II)) salts:<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> </p> PbO + <a href="/facts/Water/0lkXnJPK">H2O</a> + OH− → [Pb(OH)3]− <h2 id="applications">Applications</h2> <p>PbO is used extensively in making glass. Depending on the glass, the benefit of using PbO in glass can be one or more of increasing the <a href="/facts/Refractive_index/yjkzvgeE">refractive index</a> of the glass, increasing the <a href="/facts/Dispersion_(optics)/cUdHnYXz">dispersion</a> (i. e. reducing the <a href="/facts/Abbe_number/lcWFqTw4">Abbe number</a>) of the glass, decreasing the <a href="/facts/Viscosity/QLVfrdCz">viscosity</a> of the glass, increasing the electrical <a href="/facts/Resistivity/akyCKvMy">resistivity</a> of the glass, and increasing the ability of the glass to absorb <a href="/facts/X-rays/wseP79cN">X-rays</a>. Adding PbO to industrial <a href="/facts/Ceramics/9JKudpqX">ceramics</a> (as well as glass) makes the materials more magnetically and electrically inert (by raising their <a href="/facts/Curie_temperature/ygotSuMg">Curie temperature</a>) and it is often used for this purpose.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a> Historically PbO was also used extensively in <a href="/facts/Ceramic_glaze/eWJqJTYk">ceramic glazes</a> for household ceramics, and it is still used, but not extensively any more. Other less dominant applications include the <a href="/facts/Vulcanization/jmBUqGaz">vulcanization</a> of rubber and the production of certain pigments and paints.<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a> PbO is used in <a href="/facts/Cathode-ray_tube/8NVGx5C7">cathode-ray tube</a> glass to block <a href="/facts/X-ray/wseP79cN">X-ray</a> emission, but mainly in the neck and funnel of the tube, because it can cause discoloration when used in the faceplate. <a href="/facts/Strontium_oxide/hxr7KKj5">Strontium oxide</a> and <a href="/facts/Barium_oxide/85GNJ93P">Barium oxide</a> are preferred for the faceplate.<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a> </p><p>The consumption of lead, and hence the processing of PbO, correlates with the number of automobiles, because lead remains the key component of automotive <a href="/facts/Lead%E2%80%93acid_battery/84b8hALA">lead–acid batteries</a>.<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a> </p> <h3>Niche or declining uses</h3> <p>A mixture of PbO with <a href="/facts/Glycerine/sRQ6NBQQ">glycerine</a> sets to a hard, waterproof <a href="/facts/Cement/VfDMkk12">cement</a> that has been used to join the flat glass sides and bottoms of <a href="/facts/Aquarium/vM9WdGKC">aquariums</a>, and was also once used to seal glass panels in window frames. It is a component of <a href="/facts/Lead_paint/6PUVcrM6">lead paints</a>. </p><p>PbO was one of the raw materials for <a href="/facts/Century_egg/y8JMVhrj">century eggs</a>, a type of <a href="/facts/Chinese_cuisine/deFGefLG">Chinese</a> preserved <a href="/facts/Egg_as_food/dRLxAGev">egg</a>. but it has been gradually replaced due to health problems. It was an unscrupulous practice in some small factories but it became rampant in <a href="/facts/China/lTjIXY5p">China</a> and forced many honest manufacturers to label their boxes "lead-free" after the scandal went mainstream in 2013. </p><p>In powdered tetragonal litharge form, it can be mixed with <a href="/facts/Linseed_oil/v0XdLFcr">linseed oil</a> and then boiled to create a weather-resistant <a href="/facts/Sizing/bwdFfFp2">sizing</a> used in <a href="/facts/Gilding/Q109QPJs">gilding</a>. 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. </p><p>PbO is used in certain <a href="/facts/Condensation_reaction/wMG0F6La">condensation reactions</a> in <a href="/facts/Organic_synthesis/aprl6Iq7">organic synthesis</a>.<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a> </p><p>PbO is the input photoconductor in a video camera tube called the <a href="/facts/Plumbicon/eVaJgDlD">Plumbicon</a>. </p> <h2 id="health-issues">Health issues</h2> <p class="note">Main article: <a href="/facts/Lead_poisoning/STwlKj7c">Lead poisoning</a></p> <p>Lead oxide is toxic and irritate to skin, eyes, and respiratory tract. It affects gum tissue, the central nervous system, the kidneys, the blood, and the reproductive system. It can <a href="/facts/Bioaccumulate/KaHzFKnL">bioaccumulate</a> in plants and in mammals.<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a> </p> <h2 id="external-links">External links</h2> <ul><li><a href="https://www.atsdr.cdc.gov/csem/csem.html">Case Studies in Environmental Medicine - Lead Toxicity</a></li> <li><a href="https://www.atsdr.cdc.gov/csem/csem.html">ToxFAQs: Lead</a></li> <li><a href="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</a></li> <li><a href="http://www.webelements.com/compounds/lead/lead_oxide.html">Webelements PbO</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 382–387. ISBN 978-0-08-037941-8. <a href="978-0-08-037941-8" target="_blank">978-0-08-037941-8</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Abdel-Rehim, A. M. (2006). "Thermal and XRD analysis of Egyptian galena". Journal of Thermal Analysis and Calorimetry. 86 (2): 393–401. doi:10.1007/s10973-005-6785-6. S2CID 96393940. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Dix, J. E. (1987-02-01). "A comparison of barton-pot and ball-mill processes for making leady oxide". Journal of Power Sources. 19 (2): 157–161. Bibcode:1987JPS....19..157D. doi:10.1016/0378-7753(87)80024-1. ISSN 0378-7753. <a href="https://dx.doi.org/10.1016/0378-7753%2887%2980024-1" target="_blank">https://dx.doi.org/10.1016/0378-7753%2887%2980024-1</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Dix, J. E. (1987-02-01). "A comparison of barton-pot and ball-mill processes for making leady oxide". Journal of Power Sources. 19 (2): 157–161. Bibcode:1987JPS....19..157D. doi:10.1016/0378-7753(87)80024-1. ISSN 0378-7753. <a href="https://dx.doi.org/10.1016/0378-7753%2887%2980024-1" target="_blank">https://dx.doi.org/10.1016/0378-7753%2887%2980024-1</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Pavlov, D. (2017). Lead-acid batteries : science and technology : a handbook of lead-acid battery technology and its influence on the product (2 ed.). Saint Louis. ISBN 978-0-444-59560-7. OCLC 978538577.{{cite book}}: CS1 maint: location missing publisher (link) <a href="978-0-444-59560-7" target="_blank">978-0-444-59560-7</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Dix, J. E. (1987-02-01). "A comparison of barton-pot and ball-mill processes for making leady oxide". Journal of Power Sources. 19 (2): 157–161. Bibcode:1987JPS....19..157D. doi:10.1016/0378-7753(87)80024-1. ISSN 0378-7753. <a href="https://dx.doi.org/10.1016/0378-7753%2887%2980024-1" target="_blank">https://dx.doi.org/10.1016/0378-7753%2887%2980024-1</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Pavlov, D. (2017). Lead-acid batteries : science and technology : a handbook of lead-acid battery technology and its influence on the product (2 ed.). Saint Louis. ISBN 978-0-444-59560-7. OCLC 978538577.{{cite book}}: CS1 maint: location missing publisher (link) <a href="978-0-444-59560-7" target="_blank">978-0-444-59560-7</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Wells, A. F. (1984), Structural Inorganic Chemistry (5th ed.), Oxford: Clarendon Press, ISBN 0-19-855370-6[page needed] <a href="0-19-855370-6" target="_blank">0-19-855370-6</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>A simple example is given in Anil Kumar De (2007). "§9.2.6 Lead (Pb): Lead Monoxide PbO". A Textbook Of Inorganic Chemistry. New Age International. p. 383. ISBN 978-81-224-1384-7. A more complex example is in Turova, N.Y. (2002). "§9.4 Germanium, tin, lead alkoxides". The Chemistry of Metal Alkoxides. Springer. p. 115. ISBN 978-0-7923-7521-0. <a href="978-81-224-1384-7978-0-7923-7521-0" target="_blank">978-81-224-1384-7978-0-7923-7521-0</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Rowe, David John (1983). Lead Manufacturing in Britain: A History. Croom Helm. p. 16. ISBN 978-0-7099-2250-6. <a href="978-0-7099-2250-6" target="_blank">978-0-7099-2250-6</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 382–387. ISBN 978-0-08-037941-8. <a href="978-0-08-037941-8" target="_blank">978-0-08-037941-8</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Pirovano, Caroline; Islam, M. Saiful; Vannier, Rose-Noëlle; Nowogrocki, Guy; Mairesse, Gaëtan (2001). "Modelling the crystal structures of Aurivillius phases". Solid State Ion. 140 (1–2): 115–123. doi:10.1016/S0167-2738(01)00699-3. <a href="/wiki/Saiful_Islam_(professor)" target="_blank">/wiki/Saiful_Islam_(professor)</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>"ICSD Entry: 94333". Cambridge Structural Database: Access Structures. Cambridge Crystallographic Data Centre. Retrieved 2021-06-01. <a href="https://www.ccdc.cam.ac.uk/structures/Search?Ccdcid=1653774&DatabaseToSearch=Published" target="_blank">https://www.ccdc.cam.ac.uk/structures/Search?Ccdcid=1653774&DatabaseToSearch=Published</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Holleman, Arnold Frederik; Wiberg, Egon (2001), Wiberg, Nils (ed.), Inorganic Chemistry, translated by Eagleson, Mary; Brewer, William, San Diego/Berlin: Academic Press/De Gruyter, ISBN 0-12-352651-5[page needed] <a href="0-12-352651-5" target="_blank">0-12-352651-5</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Chapter 9, "Lead Compounds", in the book Ceramic and Glass Materials: Structure, Properties and Processing, published by Springer, year 2008. <a href="https://books.google.com/books?id=ASIYuNCp81YC&pg=PA165" target="_blank">https://books.google.com/books?id=ASIYuNCp81YC&pg=PA165</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>Carr, Dodd S. (2005). "Lead Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a15_249. ISBN 978-3-527-30673-2. <a href="978-3-527-30673-2" target="_blank">978-3-527-30673-2</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>Compton, Kenneth (5 December 2003). Image Performance in CRT Displays. SPIE Press. ISBN 9780819441447 – via Google Books. <a href="9780819441447" target="_blank">9780819441447</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>Sutherland, Charles A.; Milner, Edward F.; Kerby, Robert C.; Teindl, Herbert; Melin, Albert; Bolt, Hermann M. "Lead". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a15_193.pub2. ISBN 978-3-527-30673-2. <a href="978-3-527-30673-2" target="_blank">978-3-527-30673-2</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>Corson, B. B. (1936). "1,4-Diphenylbutadiene". Organic Syntheses. 16: 28; Collected Volumes, vol. 2, p. 229. <a href="http://www.orgsyn.org/demo.aspx?prep=CV2P0229" target="_blank">http://www.orgsyn.org/demo.aspx?prep=CV2P0229</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> <li id="fn:20"><p>"Lead(II) oxide". International Occupational Safety and Health Information Centre. Archived from the original on 2011-12-15. Retrieved 2009-06-06. <a href="https://web.archive.org/web/20111215095749/http://www.ilo.org/safework_bookshelf/english?d&nd=857171610" target="_blank">https://web.archive.org/web/20111215095749/http://www.ilo.org/safework_bookshelf/english?d&nd=857171610</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> </ol>