Lead tetroxide 1830570 222498491 2008-06-29T17:41:40Z 71.104.18.213 /* Use */ {{Chembox new | ImageFile = Red lead.jpg | ImageSize = 250px | ImageName = Red lead powder | IUPACName = Lead(II,IV) oxide | OtherNames = | Section1 = {{Chembox Identifiers | CASNo = 1314.41-6 | PubChem = | SMILES = }} | Section2 = {{Chembox Properties | Formula = Pb<sub>3</sub>O<sub>4</sub> | MolarMass = 685.598 g/mol | Appearance = orange red powder | Density = 8.3 g/cm<sup>3</sup> | MeltingPt = 500°C | BoilingPt = | Solubility = }} | Section3 = {{Chembox Hazards | MainHazards = | FlashPt = | Autoignition = }} }} [[Image:Red-lead-unit-cell-3D-balls.png|thumb|right|[[Crystal structure#Unit cell|Unit cell]] of Pb<sub>3</sub>O<sub>4</sub>]] [[Image:Red-lead-3D-balls.png|thumb|right|Part of red lead's crystal structure]] '''Red lead''', also called '''minium''', '''lead tetroxide''' or '''triplumbic tetroxide''', is a bright red or orange [[crystalline]] or [[amorphous]] [[pigment]]. Its [[Latin]] name ''minium'' originates from the [[Minius River]] in northwest [[Spain]] where it was first mined. Natural minium is uncommon, forming only in extreme oxidizing conditions of lead ore bodies. The best specimens known come from [[Broken Hill]], [[New South Wales]], [[Australia]], where they formed as the result of a mine fire <ref> [http://www.galleries.com/minerals/oxides/minium/minium.htm Minium] </ref>. A map and list of known occurrences is available [http://www.mindat.org/show.php?id=2721&ld=1#themap here]. The melting point of lead tetroxide is 500 °C, at which it decomposes to [[lead(II) oxide]] and [[oxygen]]. Chemically red lead is [[lead]] [[oxide|tetroxide]], Pb<sub>3</sub>O<sub>4</sub>, or 2PbO.PbO<sub>2</sub>. It is used in the manufacture of [[battery (electricity)|batteries]], [[lead glass]] and [[rust]]-proof [[paint]]. Red lead is virtually insoluble in water. However, it is soluble in [[hydrochloric acid]] present in the [[stomach]], and therefore it is [[toxic]] when ingested. It is also insoluble in alcohol. It dissolves in hydrochloric acid, [[glacial acetic acid]], and diluted mixture of [[nitric acid]] and [[hydrogen peroxide]]. == Preparation == Lead tetroxide is prepared by [[calcination]] of [[lead(II) oxide]] (also called [[litharge]]) in air at about 450 to 480 °C: : 6 PbO + O<sub>2</sub> → 2 Pb<sub>3</sub>O<sub>4</sub> The resulting material is contaminated with lead(II) oxide. If a pure compound is desired, PbO can be removed by a [[potassium hydroxide]] solution: : PbO + KOH + H<sub>2</sub>O → K[Pb(OH)<sub>3</sub>]<sub>(aq)</sub> Another method of preparation relies on annealing of [[lead carbonate]] ([[cerussite]]) in air: : 6 PbCO<sub>3</sub> + O<sub>2</sub> → 2 Pb<sub>3</sub>O<sub>4</sub> + 6 CO<sub>2</sub> Yet another method is oxidative annealing of [[lead white]]: : 3 Pb<sub>2</sub>CO<sub>3</sub>(OH)<sub>2</sub> + O<sub>2</sub> → 2 Pb<sub>3</sub>O<sub>4</sub> + 3 CO<sub>2</sub> + 3 H<sub>2</sub>O In solution, lead tetroxide can be prepared eg. by reaction of [[potassium plumbate]] with [[lead acetate]]: : K<sub>2</sub>PbO<sub>3</sub> + 2 Pb(OCOCH<sub>3</sub>)<sub>2</sub> + H<sub>2</sub>O → Pb<sub>3</sub>O<sub>4</sub> + 2 KOCOCH<sub>3</sub> + 2 CH<sub>3</sub>COOH yielding yellow insoluble lead tetroxide [[monohydrate]], Pb<sub>3</sub>O<sub>4</sub>.H<sub>2</sub>O, which can be turned into the anhydrous form by gentle heating. == Chemical properties == With iron oxides and with elementary [[iron]], lead tetroxide forms insoluble iron(II) and iron(III) [[plumbate]]s, which is the basis of the anti-[[corrosion|corrosive]] properties of lead-based paints applied to iron objects. When heated to 500 °C, it decomposes to lead(II) oxide and oxygen. At 580 °C, the reaction is complete. : 2 Pb<sub>3</sub>O<sub>4</sub> → 6 PbO + O<sub>2</sub> [[Nitric acid]] dissolves the lead(II) oxide component, leaving behind the insoluble [[lead(IV) oxide]]: : Pb<sub>3</sub>O<sub>4</sub> + 4 HNO<sub>3</sub> → PbO<sub>2</sub> + 2 Pb(NO<sub>3</sub>)<sub>2</sub> + 2 H<sub>2</sub>O == Use == Lead tetroxide is most often used as a [[pigment]] for [[undercoat]] [[paint]]s for [[iron]] objects. Due to its [[toxicity]] its use is being limited. In past it was used in combination with linseed oil as a thick, long-protecting anticorrosive paint. Also combination of minium and linen fibres was used for [[plumbing]], now replaced with PTFE tape. Currently it is mostly used for manufacture of [[glass]], especially [[lead glass]]. It finds limited use in some amateur [[pyrotechnics]] as a relatively potent [[oxidizer]]. == Physiological effects == {{main|Lead poisoning}} When breathed in, lead tetroxide irritates lungs. In case of high dose, the victim feels metallic taste in mouth, chest pain, and abdominal pain. When ingested, it gets dissolved in the [[gastric acid]] and gets absorbed, leading to lead poisoning. High concentrations can be absorbed through skin as well; therefore it is important to keep the safety precautions when working with lead-based paint. Long-term contact with lead tetroxide may lead to accumulation of lead compounds in organism, with development of symptoms of acute lead poisoning. Chronic poisoning displays as agitation, irritability, vision disorders, [[hypertension]], and usually also by grayish hue of face. Lead tetroxide was shown to be [[carcinogenic]] for laboratory animals. Its carcinogenicity for humans was not proven. [[Image:Minium- BYU.jpg|thumb|left|'''Minium''' from a mine fire at [[Broken Hill]], [[Australia]] ]] ==History== Lead tetroxide was used as a red pigment in [[ancient Rome]], where it was prepared by [[calcination]] of [[lead white]]. In the ancient and medieval periods it was used as a pigment in the production of [[illuminated manuscript]]s, and gave its name to the ''minium'' or [[miniature (illuminated manuscript)|miniature]], a style of picture painted with the colour. As a finely divided powder, it was also sprinkled on [[dielectric]] surfaces to study [[Lichtenberg figures]]. It was first isolated as a pure compound by [[Alchemy and chemistry in Islam|Arabic chemists]] and was clearly described by [[Muhammad ibn Zakarīya Rāzi]] (Rhazes) in the early 10th century.<ref name=Hassan-Alchemy>{{cite web |url= http://www.history-science-technology.com/Articles/articles%2010.htm |title= Arabic Alchemy: Science of the Art |accessdate=2008-03-29 |last=Hassan |first=Ahmad Y |authorlink=Ahmad Y Hassan |work=History of Science and Technology in Islam}}</ref> ==References== {{reflist}} ==External links== * [http://www.npi.gov.au/database/substance-info/profiles/50.html National Pollutant Inventory - Lead and Lead Compounds Fact Sheet] * [http://webmineral.com/data/Minium.shtml Minium mineral data] [[Category:Oxides]] [[Category:Lead compounds]] [[Category:Inorganic pigments]] [[Category:Lead minerals]] [[Category:Oxide minerals]] [[Category:Mixed valence compounds]] [[Category:Corrosion prevention]] [[Category:Pyrotechnic oxidizers]] [[bg:Миниум]] [[ca:Mini]] [[cs:Suřík]] [[da:Mønje]] [[de:Blei(II,IV)-oxid]] [[es:Tetróxido de plomo]] [[fr:Minium]] [[it:Minio]] [[nl:Loodmenie]] [[ja:鉛丹]] [[pl:Minia ołowiowa]] [[ru:Сурик (свинцовый)]] [[fi:Mönjä]] [[sv:Blymönja]] [[zh:四氧化三鉛]]