Lead(II,IV) oxide
This article needs additional citations for verification. (December 2023) |
Names | |
---|---|
Preferred IUPAC name
Lead tetroxide [1] | |
Other names
Minium, red lead, triplumbic tetroxide
| |
Identifiers | |
3D model (
JSmol ) |
|
ChemSpider | |
ECHA InfoCard
|
100.013.851 |
EC Number |
|
PubChem CID
|
|
UNII | |
UN number | 1479 |
CompTox Dashboard (EPA)
|
|
| |
| |
Properties | |
Pb3O4 | |
Molar mass | 685.6 g·mol−1 |
Appearance | Vivid orange crystals |
Density | 8.3 g/cm3 |
Melting point | 500 °C (decomposition) |
Vapor pressure | 1.3 kPa (at 0 °C) |
Structure | |
Tetragonal, tP28
| |
P42/mbc, No. 135 | |
Hazards | |
GHS labelling: | |
Danger | |
H272, H302, H332, H360, H373, H410 | |
P201, P220, P273, P308+P313, P501 | |
NFPA 704 (fire diamond) | |
Related compounds | |
Lead(II) oxide Lead(IV) oxide | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|
Lead(II,IV) oxide, also called red lead or
Structure
Lead(II,IV) oxide is lead(II) orthoplumbate(IV) [Pb2+]2[PbO4−4].
-
Part of tetragonal red lead's crystal structure
Preparation
Lead(II,IV) oxide is prepared by calcination of lead(II) oxide (PbO; also called litharge) in air at about 450–480 °C:[5]
- 6 PbO + O2 → 2 Pb3O4
The resulting material is contaminated with PbO. If a pure compound is desired, PbO can be removed by a potassium hydroxide solution:
- PbO + KOH + H2O → K[Pb(OH)3]
Another method of preparation relies on
- 6 PbCO3 + O2 → 2 Pb3O4 + 6 CO2
Yet another method is
- 3 Pb2CO3(OH)2 + O2 → 2 Pb3O4 + 3 CO2 + 3 H2O
In solution, lead(II,IV) oxide can be prepared by reaction of potassium
- K2PbO3 + 2 Pb(OCOCH3)2 + H2O → Pb3O4 + 2 KOCOCH3 + 2 CH3COOH
Natural
Reactions
Red lead is virtually insoluble in water and in
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
- Pb3O4 + 4 HNO3 → PbO2 + 2 Pb(NO3)2 + 2 H2O
With iron oxides and with elemental iron, lead(II,IV) oxide forms insoluble iron(II) and iron(III) plumbates, which is the basis of the anticorrosive properties of lead-based paints applied to iron objects.
Use
Red lead has been used as a
Red lead is used as a curing agent in some polychloroprene rubber compounds. It is used in place of magnesium oxide to provide better water resistance properties.
Red lead was used for engineer's scraping, before being supplanted by engineer's blue.
It is also used as an adulterating agent in turmeric powder.
Physiological effects
When inhaled, lead(II,IV) oxide irritates the lungs. In case of high dose, the victim experiences a metallic taste, chest pain, and abdominal pain. When ingested, it is dissolved in the gastric acid and absorbed, leading to lead poisoning. High concentrations can be absorbed through skin as well, and it is important to follow safety precautions when working with lead-based paint.
Long-term contact with lead(II,IV) oxide may lead to accumulation of lead compounds in organisms, with development of symptoms of acute lead poisoning. Chronic poisoning displays as agitation, irritability, vision disorders, hypertension, and a grayish facial hue.
Lead(II,IV) oxide was shown to be
History
This compound's
Lead(II,IV) oxide was used as a red pigment in ancient Rome, where it was prepared by calcination of white lead. 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.
Made into a paint with linseed oil, red lead was used as a durable paint to protect exterior ironwork. In 1504 the portcullis at Stirling Castle in Scotland was painted with red lead, as were cannons including Mons Meg.[7]
As a finely divided powder, it was also sprinkled on
In
It was also used before the 18th century as medicine.[9]
See also
- Lead paint
- Lead(II) oxide, PbO
- Lead(IV) oxide, PbO2
- List of inorganic pigments
- Minium (mineral)
- Minium (pigment)
References
- ^ "VOLUNTARY RISK ASSESSMENT REPORT ON LEAD AND SOME INORGANIC LEAD COMPOUNDS". Retrieved 2012-12-25.
- ISBN 978-0-08-037941-8.
- ISBN 0-12-352651-5.
- .
- ISBN 978-3527306732.
- ^ Minium
- ^ James Balfour Paul, Accounts of the Treasurer of Scotland, vol. 2 (Edinburgh, 1900), p. 277.
- S2CID 37730169.
- ^ "The London Lancet: A Journal of British and Foreign Medicine, Physiology, Surgery, Chemistry, Criticism, Literature and News". 1853.