Lead tetroxide


Lead tetroxide

Chembox new
ImageFile = Red lead.jpg
ImageSize = 250px
ImageName = Red lead powder
IUPACName = dilead(II) lead(IV) oxide
OtherNames =
Section1 = Chembox Identifiers
CASNo = 1314-41-6
PubChem =
SMILES =

Section2 = Chembox Properties
Formula = Pb3O4 2PbO.PbO2
MolarMass = 685.598 g/mol
Appearance = orange red powder
Density = 8.3 g/cm3
MeltingPt = 500°C
BoilingPt =
Solubility =

Section3 = Chembox Hazards
MainHazards =
FlashPt =
Autoignition =

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 [ [http://www.galleries.com/minerals/oxides/minium/minium.htm Minium] ] . 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 tetroxide, Pb3O4, or 2PbO.PbO2. It is used in the manufacture of 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 + O2 → 2 Pb3O4The 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 + H2O → K [Pb(OH)3] (aq)

Another method of preparation relies on annealing of lead carbonate (cerussite) in air:: 6 PbCO3 + O2 → 2 Pb3O4 + 6 CO2

Yet another method is oxidative annealing of lead white:: 3 Pb2CO3(OH)2 + O2 → 2 Pb3O4 + 3 CO2 + 3 H2O

In solution, lead tetroxide can be prepared eg. by reaction of potassium plumbate with lead acetate:: K2PbO3 + 2 Pb(OCOCH3)2 + H2O → Pb3O4 + 2 KOCOCH3 + 2 CH3COOHyielding yellow insoluble lead tetroxide monohydrate, Pb3O4.H2O, 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) plumbates, which is the basis of the anti-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 Pb3O4 → 6 PbO + O2

Nitric acid dissolves the lead(II) oxide component, leaving behind the insoluble lead(IV) oxide:: Pb3O4 + 4 HNO3 → PbO2 + 2 Pb(NO3)2 + 2 H2O

Use

Lead tetroxide is most often used as a pigment for undercoat paints 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

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.

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 manuscripts, and gave its name to the "minium" or 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 Arabic chemists and was clearly described by Muhammad ibn Zakarīya Rāzi (Rhazes) in the early 10th century.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]

References

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]


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  • lead tetroxide — minium min i*um (?; 277), n. [L. minium, an Iberian word, the Romans getting all their cinnabar from Spain; cf. Basque armine[ a].] (Chem.) A heavy, brilliant red pigment, consisting of an oxide of lead, {Pb3O4}, obtained by exposing lead or… …   The Collaborative International Dictionary of English

  • lead processing — Introduction       preparation of the ore for use in various products.       Lead (Pb) is one of the oldest metals known, being one of seven metals used in the ancient world (the others are gold, silver, copper, iron, tin, and mercury). Its low… …   Universalium

  • lead orthoplumbate — minium min i*um (?; 277), n. [L. minium, an Iberian word, the Romans getting all their cinnabar from Spain; cf. Basque armine[ a].] (Chem.) A heavy, brilliant red pigment, consisting of an oxide of lead, {Pb3O4}, obtained by exposing lead or… …   The Collaborative International Dictionary of English

  • lead oxide — minium min i*um (?; 277), n. [L. minium, an Iberian word, the Romans getting all their cinnabar from Spain; cf. Basque armine[ a].] (Chem.) A heavy, brilliant red pigment, consisting of an oxide of lead, {Pb3O4}, obtained by exposing lead or… …   The Collaborative International Dictionary of English

  • lead oxide yellow — massicot mas si*cot, n. [F. massicot; E. masticot is a corruption.] (Chem.) Lead monoxide (also called {Lead protoxide}), {PbO}, obtained as a yellow amorphous powder, the fused and crystalline form of which is called {litharge}; lead ocher. It… …   The Collaborative International Dictionary of English

  • Lead protoxide — massicot mas si*cot, n. [F. massicot; E. masticot is a corruption.] (Chem.) Lead monoxide (also called {Lead protoxide}), {PbO}, obtained as a yellow amorphous powder, the fused and crystalline form of which is called {litharge}; lead ocher. It… …   The Collaborative International Dictionary of English

  • Lead(II) nitrate — Lead(II) nitrate …   Wikipedia

  • lead — A metallic element, atomic no. 82, atomic wt. 207.2. SYN: plumbum. l. acetate has been used as an astringent in diarrhea, and in aqueous solution as a wet dressing in certain dermatoses. SYN: sugar of l.. black l …   Medical dictionary

  • red lead — minium min i*um (?; 277), n. [L. minium, an Iberian word, the Romans getting all their cinnabar from Spain; cf. Basque armine[ a].] (Chem.) A heavy, brilliant red pigment, consisting of an oxide of lead, {Pb3O4}, obtained by exposing lead or… …   The Collaborative International Dictionary of English

  • red lead — noun a bright red, poisonous oxide of lead, PbO, used as a pigment and in glass and ceramics Syn: lead tetroxide, minium …   Wiktionary