Lead(II,IV) oxide, also called red lead or minium, is the inorganic compound with the formula . A bright red or orange solid, it is used as pigment, in the manufacture of batteries, and

rust Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO(OH) ...

proof primer paints. It is an example of a

mixed valence compound Mixed valence complexes contain an element which is present in more than one oxidation state. Well-known mixed valence compounds include the Creutz–Taube complex, Prussian blue, and molybdenum blue. Many solids are mixed-valency including ...

, being composed of both Pb(II) and Pb(IV) in the ratio of two to one.

Structure

Lead(II,IV) oxide is lead(II) orthoplumbate(IV) . It has a tetragonal crystal structure at

room temperature Room temperature, colloquially, denotes the range of air temperatures most people find comfortable indoors while dressed in typical clothing. Comfortable temperatures can be extended beyond this range depending on humidity, air circulation, and ...

, which then transforms to an

orthorhombic In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic Lattice (group), lattices result from stretching a cubic crystal system, cubic lattice along two of its orthogonal pairs by two different factors, res ...

(

Pearson symbol The Pearson symbol, or Pearson notation, is used in crystallography as a means of describing a crystal structure. It was originated by William Burton Pearson and is used extensively in Pearson's handbook of crystallographic data for intermetallic p ...

''oP''28,

Space group In mathematics, physics and chemistry, a space group is the symmetry group of a repeating pattern in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of the pattern that ...

Pbam, No. 55) form at temperature . This phase transition only changes the symmetry of the crystal and slightly modifies the interatomic distances and angles. File:Red-lead-unit-cell-3D-balls.png,

Unit cell In geometry, biology, mineralogy and solid state physics, a unit cell is a repeating unit formed by the vectors spanning the points of a lattice. Despite its suggestive name, the unit cell (unlike a unit vector In mathematics, a unit vector i ...

of tetragonal
(Key: Pb O) File:Red-lead-3D-balls.png, Part of tetragonal red lead's crystal structure

Preparation

Lead(II,IV) oxide is prepared by

calcination Calcination is thermal treatment of a solid chemical compound (e.g. mixed carbonate ores) whereby the compound is raised to high temperature without melting under restricted supply of ambient oxygen (i.e. gaseous O2 fraction of air), generally f ...

lead(II) oxide Lead(II) oxide, also called lead monoxide, is the inorganic compound with the molecular formula Pb O. It occurs in two polymorphs: litharge having a tetragonal crystal structure, and massicot having an orthorhombic crystal structure. Modern ...

(PbO; also called

litharge Litharge (from Greek , 'stone' + 'silver' ) is one of the natural mineral forms of lead(II) oxide, PbO. Litharge is a secondary mineral which forms from the oxidation of galena ores. It forms as coatings and encrustations with internal tetr ...

) in air at about 450–480 °C: : The resulting material is contaminated with PbO. If a pure compound is desired, PbO can be removed by a

potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which utili ...

solution: : Another method of preparation relies on annealing of

lead(II) carbonate Lead(II) carbonate is the chemical compound with the chemical formula . It is a white, toxic solid. It occurs naturally as the mineral cerussite. Structure Like all metal carbonates, lead(II) carbonate adopts a dense, highly crosslinked structure ...

(

cerussite Cerussite (also known as lead carbonate or white lead ore) is a mineral consisting of lead carbonate with the chemical formula PbCO3, and is an important ore of lead. The name is from the Latin ''cerussa'', white lead. ''Cerussa nativa'' was ...

) in air: : Yet another method is

oxidative Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...

annealing of

white lead White lead is the basic lead carbonate 2PbCO3·Pb(OH)2. It is a complex Salt (chemistry), salt, containing both carbonate and hydroxide ions. White lead occurs naturally as a mineral, in which context it is known as hydrocerussite, a hydrate of ...

: : In solution, lead(II,IV) oxide can be prepared by reaction of potassium

plumbate In chemistry, a plumbate often refers to compounds that can be viewed as derivatives of the hypothetical anion. Examples Halides Salts of , , , etc. are labeled as iodoplumbates. Lead perovskite semiconductors are often described as plumbates. ...

with

lead(II) acetate Lead(II) acetate is a white crystalline chemical compound with a slightly sweet taste. Its chemical formula is usually expressed as or , where Ac represents the acetyl group. Like many other lead compounds, it causes lead poisoning. Lead aceta ...

, yielding yellow insoluble lead(II,IV) oxide

monohydrate In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understo ...

, which can be turned into the anhydrous form by gentle heating: : Natural minium is uncommon, forming only in extreme oxidizing conditions of

lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...

ore bodies. The best known natural specimens come from

Broken Hill Broken Hill is a city in the Far West (New South Wales), far west region of outback New South Wales, Australia. An inland mining city, it is near the border with South Australia on the crossing of the Barrier Highway (A32) and the Silver City Hi ...

New South Wales New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...

, Australia, where they formed as the result of a

mine fire A coal-seam fire is a burning of an outcrop or underground coal seam. Most coal-seam fires exhibit smouldering combustion, particularly underground coal-seam fires, because of limited atmospheric oxygen availability. Coal-seam fire instances ...

Reactions

Red lead is virtually insoluble in water and in

ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...

. However, it is soluble in

hydrochloric acid Hydrochloric acid, also known as muriatic acid or spirits of salt, is an aqueous solution of hydrogen chloride (HCl). It is a colorless solution with a distinctive pungency, pungent smell. It is classified as a acid strength, strong acid. It is ...

present in the

stomach The stomach is a muscular, hollow organ in the upper gastrointestinal tract of Human, humans and many other animals, including several invertebrates. The Ancient Greek name for the stomach is ''gaster'' which is used as ''gastric'' in medical t ...

, and is therefore

toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...

when ingested. It also dissolves in

glacial acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compone ...

and a diluted mixture of

nitric acid Nitric acid is an inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but samples tend to acquire a yellow cast over time due to decomposition into nitrogen oxide, oxides of nitrogen. Most com ...

and

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscosity, viscous than Properties of water, water. It is used as an oxidizer, bleaching agent, and antiseptic, usua ...

. When heated to 500 °C, it decomposes to lead(II) oxide and oxygen. At 580 °C, the reaction is complete. :

Nitric acid Nitric acid is an inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but samples tend to acquire a yellow cast over time due to decomposition into nitrogen oxide, oxides of nitrogen. Most com ...

dissolves the lead(II) oxide component, leaving behind the insoluble

lead(IV) oxide Lead(IV) oxide, commonly known as lead dioxide, is an inorganic compound with the chemical formula . It is an oxide where lead is in an oxidation state of +4. It is a dark-brown solid which is insoluble in water. It exists in two crystalline forms. ...

: : With iron oxides and with elemental

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

, lead(II,IV) oxide forms insoluble iron(II) and iron(III)

s, which is the basis of the anticorrosive properties of lead-based paints applied to iron objects.

Use

Red lead has been used as a

pigment A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...

for

primer Primer may refer to: Arts, entertainment, and media Films * ''Primer'' (film), a 2004 feature film written and directed by Shane Carruth * ''Primer'' (video), a documentary about the funk band Living Colour Literature * Primer (textbook), a te ...

paint Paint is a material or mixture that, when applied to a solid material and allowed to dry, adds a film-like layer. As art, this is used to create an image or images known as a painting. Paint can be made in many colors and types. Most paints are ...

s for

objects. Due to its

toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacteria, bacterium, or plant, as well as the effect o ...

, its use is being limited. It finds limited use in some amateur

pyrotechnics Pyrotechnics is the science and craft of creating fireworks, but also includes safety matches, oxygen candles, Pyrotechnic fastener, explosive bolts (and other fasteners), parts of automotive airbags, as well as gas-pressure blasting in mining, q ...

as a

delay charge Delay composition, also called delay charge or delay train, is a pyrotechnic composition, a sort of pyrotechnic initiator, a mixture of oxidizer and fuel that burns in a slow, constant rate that should not be significantly dependent on temperature ...

and was used in the past in the manufacture of

dragon's egg ''Dragon's Egg'' is a 1980 hard science fiction novel by American writer Robert L. Forward. In the story, Dragon's Egg is a neutron star with a surface gravity 67 billion times that of Earth, and inhabited by cheela, intelligent creatur ...

pyrotechnic stars Pyrotechnic stars are pellets of pyrotechnic composition which may contain metal powders, salts or other compounds that, when ignited, burn a certain color or make a certain spark effect. They are a part of all projectile-type fireworks. The mo ...

. Red lead is used as a curing agent in some

polychloroprene Neoprene (also polychloroprene) is a family of synthetic rubbers that are produced by polymerization of chloroprene.Werner Obrecht, Jean-Pierre Lambert, Michael Happ, Christiane Oppenheimer-Stix, John Dunn and Ralf Krüger "Rubber, 4. Emulsion Rub ...

rubber compounds. It is used in place of

magnesium oxide Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...

to provide better water resistance properties. Red lead was used for engineer's

scraping Scrape, scraper or scraping may refer to: Biology and medicine * Abrasion (medical), a type of injury * Scraper (biology), grazer-scraper, a water animal that feeds on stones and other substrates by grazing algae, microorganism and other matter ...

, before being supplanted by

engineer's blue Engineer's blue (also known as scraping blue, Prussian blue, or simply bluing) is a highly pigmented paste used to assist in the mating of two or more components. History Joseph Whitworth popularized the first practical method of making accurate ...

. Although red lead still offers more accurate markings since it doesn't flow as readily as

under pressure. 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 Gastric acid or stomach acid is the acidic component – hydrochloric acid – of gastric juice, produced by parietal cells in the gastric glands of the stomach lining. In humans, the pH is between one and three, much lower than most other a ...

and absorbed, leading to

lead poisoning Lead poisoning, also known as plumbism and saturnism, is a type of metal poisoning caused by lead in the body. Symptoms may include abdominal pain, constipation, headaches, irritability, memory problems, infertility, numbness and paresthesia, t ...

. 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 Hypertension, also known as high blood pressure, is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not cause symptoms i ...

, and a grayish facial hue. Lead(II,IV) oxide was shown to be

carcinogenic A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and Biological agent, biologic agent ...

for

laboratory animals Animal testing, also known as animal experimentation, animal research, and ''in vivo'' testing, is the use of animals, as model organisms, in experiments that seek answers to scientific and medical questions. This approach can be contrasted ...

. Its carcinogenicity for humans was not proven. Minium- BYU

History

This compound's

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

name ''minium'' originates from the Minius, a river in northwest

Iberia The Iberian Peninsula ( ), also known as Iberia, is a peninsula in south-western Europe. Mostly separated from the rest of the European landmass by the Pyrenees, it includes the territories of peninsular Spain and Continental Portugal, compri ...

where it was first mined. Lead(II,IV) oxide was used as a red pigment in

ancient Rome In modern historiography, ancient Rome is the Roman people, Roman civilisation from the founding of Rome, founding of the Italian city of Rome in the 8th century BC to the Fall of the Western Roman Empire, collapse of the Western Roman Em ...

, where it was prepared by

. In the ancient and medieval periods it was used as a pigment in the production of

illuminated manuscript An illuminated manuscript is a formally prepared manuscript, document where the text is decorated with flourishes such as marginalia, borders and Miniature (illuminated manuscript), miniature illustrations. Often used in the Roman Catholic Churc ...

s, and gave its name to the ''minium'' or miniature, a style of picture painted with the colour. Made into a paint with

linseed oil Linseed oil, also known as flaxseed oil or flax oil (in its edible form), is a colorless to yellowish oil obtained from the dried, ripened seeds of the flax plant (''Linum usitatissimum''). The oil is obtained by pressing, sometimes followed by ...

, red lead was used as a durable paint to protect exterior ironwork. In 1504 the

portcullis A portcullis () is a heavy, vertically closing gate typically found in medieval fortifications. It consists of a latticed Grille (architecture), grille made of wood and/or metal, which slides down grooves inset within each jamb of the gateway. ...

Stirling Castle Stirling Castle, located in Stirling, is one of the largest and most historically and architecturally important castles in Scotland. The castle sits atop an Intrusive rock, intrusive Crag and tail, crag, which forms part of the Stirling Sill ge ...

in Scotland was painted with red lead, as were cannons including Mons Meg. As a finely divided powder, it was also sprinkled on

dielectric In electromagnetism, a dielectric (or dielectric medium) is an Insulator (electricity), electrical insulator that can be Polarisability, polarised by an applied electric field. When a dielectric material is placed in an electric field, electric ...

surfaces to study

Lichtenberg figures A Lichtenberg figure (German: ''Lichtenberg-Figur''), or Lichtenberg dust figure, is a branching electric discharge that sometimes appears on the surface or in the interior of insulating materials. Lichtenberg figures are often associated wit ...

. In

traditional Chinese medicine Traditional Chinese medicine (TCM) is an alternative medicine, alternative medical practice drawn from traditional medicine in China. A large share of its claims are pseudoscientific, with the majority of treatments having no robust evidence ...

, red lead is used to treat ringworms and

ulceration An ulcer is a discontinuity or break in a bodily membrane that impedes normal function of the affected Organ (biology), organ. According to Robbins's pathology, "ulcer is the breach of the continuity of skin, epithelium or mucous membrane caus ...

s, though the practice is limited due to its toxicity. Also, ''azarcón'', a Mexican folk remedy for gastrointestinal disorders, contains up to 95% lead(II,IV) oxide. It was also used before the 18th century as medicine.

References

External links

National Pollutant Inventory - Lead and Lead Compounds Fact SheetMinium mineral data
{{Oxides Corrosion inhibitors Inorganic pigments Mixed valence compounds Oxides Pyrotechnic oxidizers