Lead(II) oxide

Last updated
Lead(II) oxide
Oxid olovnaty.JPG
PbO structure.png
Names
IUPAC name
Lead(II) oxide
Other names
Lead monoxide
Litharge
Massicot
Plumbous oxide
Galena
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.013.880 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 215-267-0
KEGG
PubChem CID
RTECS number
  • OG1750000
UNII
UN number 3288 2291 3077
  • InChI=1S/O.Pb
    Key: YEXPOXQUZXUXJW-UHFFFAOYSA-N
  • O=[Pb]
Properties
PbO
Molar mass 223.20 g/mol
Appearancered or yellow powder
Density 9.53 g/cm3
Melting point 888 °C (1,630 °F; 1,161 K)
Boiling point 1,477 °C (2,691 °F; 1,750 K)
α-PbO: 0.0504 g/L (25 °C)
β-PbO: 0.1065 g/L (25 °C) [1]
Solubility insoluble in dilute alkalis, alcohol
soluble in concentrated alkalis
soluble in HCl, ammonium chloride
4.20×10−5 cm3/mol
Structure
Tetragonal, tP4
P4/nmm, No. 129
Hazards
GHS labelling:
GHS-pictogram-exclam.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
Danger
H302, H332, H351, H360Df, H362, H373, H410
P201, P202, P260, P261, P263, P264, P270, P271, P273, P281, P301+P312, P304+P312, P304+P340, P308+P313, P312, P314, P330, P391, P405, P501
NFPA 704 (fire diamond)
NFPA 704.svgHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3
0
0
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
1400 mg/kg (dog, oral) [2]
Safety data sheet (SDS) ICSC 0288
Related compounds
Other anions
Lead(II) sulfide
Lead selenide
Lead telluride
Other cations
Carbon monoxide
Silicon monoxide
Germanium monoxide
Tin(II) oxide
Related lead oxides
Lead(II,IV) oxide
Lead dioxide
Related compounds
Thallium(III) oxide
Bismuth(III) oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Lead(II) oxide, also called lead monoxide, is the inorganic compound with the molecular formula Pb O. PbO occurs in two polymorphs: litharge having a tetragonal crystal structure, and massicot having an orthorhombic crystal structure. Modern applications for PbO are mostly in lead-based industrial glass and industrial ceramics, including computer components. It is an amphoteric oxide. [3]

Contents

Types

Lead oxide exists in two types:

Synthesis

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 oxides of lead in air: [4]

Thermal decomposition of lead(II) nitrate or lead(II) carbonate also results in the formation of PbO:

2 Pb(NO
3
)
2
→ 2 PbO + 4  NO
2
+ O
2
PbCO
3
→ PbO + CO2

PbO is produced on a large scale as an intermediate product in refining raw lead ores into metallic lead. The usual lead ore is galena (lead(II) sulfide). At a temperature of around 1,000 °C (1,800 °F) the sulfide is converted to the oxide: [5]

2 PbS + 3 O
2
→ 2 PbO + 2  SO2

From lead

There are two principal methods to make lead monoxide both of which resemble combustion of the lead at high temperature: [6]

Barton pot method.
The refined molten lead droplets are oxidized in a vessel under a forced air flow which carries them out to the separation system (e.g. cyclonic separators) for further processing. [6] [7] :245 Oxides produced by this method are mostly a mixture of α-PbO and β-PbO. The overall reaction is:

2Pb + O2450 °C (842 °F)2PbO

Ball mill method
The 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. [6] [7] :245

Structure

As determined by X-ray crystallography, both polymorphs, tetragonal and orthorhombic 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 stereochemically active lone pair of electrons. [8] When PbO occurs in tetragonal lattice structure it is called litharge; and when the PbO has orthorhombic lattice structure it is called massicot. The PbO can be changed from massicot to litharge or vice versa by controlled heating and cooling. [9] 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. [10] The tetragonal and orthorhombic forms of PbO occur naturally as rare minerals.

Reactions

Metallic lead is obtained by reducing PbO with carbon monoxide at around 1,200 °C (2,200 °F): [13]

PbO + CO → Pb + CO2

The red and yellow forms of this material are related by a small change in enthalpy:

PbO(red) → PbO(yellow)  ΔH = 1.6 kJ/mol

PbO is amphoteric, which means that it reacts with both acids and with bases. With acids, it forms salts of Pb2+
via the intermediacy of oxo clusters such as [Pb
6
O(OH)
6
]4+
. With strong bases, PbO dissolves to form plumbite (also called plumbate(II)) salts: [14]

PbO + H2O + OH
[Pb(OH)
3
]

Applications

The kind of lead in lead glass is normally PbO, and 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 refractive index of the glass, increasing the dispersion (i. e. reducing the Abbe number) of the glass, decreasing the viscosity of the glass, increasing the electrical resistivity of the glass, and increasing the ability of the glass to absorb X-rays. Adding PbO to industrial ceramics (as well as glass) makes the materials more magnetically and electrically inert (by raising their Curie temperature) and it is often used for this purpose. [15] Historically PbO was also used extensively in ceramic glazes for household ceramics, and it is still used, but not extensively any more. Other less dominant applications include the vulcanization of rubber and the production of certain pigments and paints. [3] PbO is used in cathode ray tube glass to block X-ray emission, but mainly in the neck and funnel of the tube, because it can cause discoloration when used in the faceplate. Strontium oxide and Barium oxide are preferred for the faceplate. [16]

The consumption of lead, and hence the processing of PbO, correlates with the number of automobiles, because lead remains the key component of automotive lead–acid batteries. [17]

Niche or declining uses

A mixture of PbO with glycerine sets to a hard, waterproof cement that has been used to join the flat glass sides and bottoms of aquariums, and was also once used to seal glass panels in window frames. It is a component of lead paints.

PbO was one of the raw materials for century eggs, a type of Chinese preserved egg. but it has been gradually replaced due to health problems. It was an unscrupulous practice in some small factories but it became rampant in China and forced many honest manufacturers to label their boxes "lead-free" after the scandal went mainstream in 2013.

In powdered tetragonal litharge form, it can be mixed with linseed oil and then boiled to create a weather-resistant sizing used in gilding. 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.

PbO is used in certain condensation reactions in organic synthesis. [18]

PbO is the input photoconductor in a video camera tube called the Plumbicon.

Health issues

PbOlabel.jpg

Lead oxide may be fatal if swallowed or inhaled. It causes irritation to skin, eyes, and respiratory tract. It affects gum tissue, the central nervous system, the kidneys, the blood, and the reproductive system. It can bioaccumulate in plants and in mammals. [19]

Related Research Articles

In chemistry, an amphoteric compound is a molecule or ion that can react both as an acid and as a base. What exactly this can mean depends on which definitions of acids and bases are being used.

<span class="mw-page-title-main">Lead(II) nitrate</span> Chemical compound

Lead(II) nitrate is an inorganic compound with the chemical formula Pb(NO3)2. It commonly occurs as a colourless crystal or white powder and, unlike most other lead(II) salts, is soluble in water.

<span class="mw-page-title-main">Lead(II) chloride</span> Chemical compound

Lead(II) chloride (PbCl2) is an inorganic compound which is a white solid under ambient conditions. It is poorly soluble in water. Lead(II) chloride is one of the most important lead-based reagents. It also occurs naturally in the form of the mineral cotunnite.

<span class="mw-page-title-main">Lead(II,IV) oxide</span> Chemical compound

Lead(II,IV) oxide, also called red lead or minium, is the inorganic compound with the formula Pb3O4. A bright red or orange solid, it is used as pigment, in the manufacture of batteries, and rustproof primer paints. It is an example of a mixed valence compound, being composed of both Pb(II) and Pb(IV) in the ratio of two to one.

<span class="mw-page-title-main">Litharge</span>

Litharge (from Greek lithargyros, lithos 'stone' + argyros 'silver' λιθάργυρος) 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 tetragonal crystal structure. It is dimorphous with the yellow orthorhombic form massicot. It forms soft (Mohs hardness of 2), red, greasy-appearing crusts with a very high specific gravity of 9.14–9.35. PbO may be prepared by heating lead metal in air at approximately 600 °C (lead melts at only 300 °C). At this temperature it is also the end product of heating of other lead oxides in air. This is often done with a set of bellows pumping air over molten lead and causing the oxidized product to slip or fall off the top into a receptacle, where it quickly solidifies in minute scales.

<span class="mw-page-title-main">Tellurium dioxide</span> Chemical compound

Tellurium dioxide (TeO2) is a solid oxide of tellurium. It is encountered in two different forms, the yellow orthorhombic mineral tellurite, β-TeO2, and the synthetic, colourless tetragonal (paratellurite), α-TeO2. Most of the information regarding reaction chemistry has been obtained in studies involving paratellurite, α-TeO2.

<span class="mw-page-title-main">Tin(II) oxide</span> Chemical compound, stannous oxide (SnO)

Tin(II) oxide is a compound with the formula SnO. It is composed of tin and oxygen where tin has the oxidation state of +2. There are two forms, a stable blue-black form and a metastable red form.

Selenic acid is the inorganic compound with the formula H2SeO4. It is an oxoacid of selenium, and its structure is more accurately described as O2Se(OH)2. It is a colorless compound. Although it has few uses, one of its salts, sodium selenate is used in the production of glass and animal feeds.

<span class="mw-page-title-main">Tin(IV) oxide</span> Chemical compound known as stannic oxide, cassiterite and tin ore

Tin(IV) oxide, also known as stannic oxide, is the inorganic compound with the formula SnO2. The mineral form of SnO2 is called cassiterite, and this is the main ore of tin. With many other names, this oxide of tin is an important material in tin chemistry. It is a colourless, diamagnetic, amphoteric solid.

<span class="mw-page-title-main">Lead dioxide</span> Chemical compound

Lead(IV) oxide, commonly known as lead dioxide, is an inorganic compound with the chemical formula PbO2. 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. It has several important applications in electrochemistry, in particular as the positive plate of lead acid batteries.

<span class="mw-page-title-main">Massicot</span>

Massicot is lead (II) oxide mineral with an orthorhombic lattice structure. Lead(II) oxide can occur in one of two lattice formats, orthorhombic and tetragonal. The red tetragonal form is called litharge. PbO can be changed from massicot to litharge by controlled heating and cooling. At room temperature massicot forms soft yellow to reddish-yellow, earthy, scaley masses which are very dense, with a specific gravity of 9.64. Massicot can be found as a natural mineral, though it is only found in minor quantities. In bygone centuries it was mined. Nowadays massicot arises during industrial processing of lead and lead oxides, especially in the glass industry, which is the biggest user of PbO.

Lead(II) hydroxide, Pb(OH)2, is a hydroxide of lead, with lead in oxidation state +2.

Lead oxides are a group of inorganic compounds with formulas including lead (Pb) and oxygen (O).

<span class="mw-page-title-main">Lead carbonate</span> Chemical compound

Lead(II) carbonate is the chemical compound with the chemical formula PbCO3. It is a white, toxic solid. It occurs naturally as the mineral cerussite.

<span class="mw-page-title-main">Lead(II) fluoride</span> Chemical compound

Lead(II) fluoride is the inorganic compound with the formula PbF2. It is a white solid. The compound is polymorphic, at ambient temperatures it exists in orthorhombic (PbCl2 type) form, while at high temperatures it is cubic (Fluorite type).

Germanium dioxide, also called germanium(IV) oxide, germania, and salt of germanium, is an inorganic compound with the chemical formula GeO2. It is the main commercial source of germanium. It also forms as a passivation layer on pure germanium in contact with atmospheric oxygen.

<span class="mw-page-title-main">Berkelium compounds</span> Chemical compounds

Berkelium forms a number of chemical compounds, where it normally exists in an oxidation state of +3 or +4, and behaves similarly to its lanthanide analogue, terbium. Like all actinides, berkelium easily dissolves in various aqueous inorganic acids, liberating gaseous hydrogen and converting into the trivalent oxidation state. This trivalent state is the most stable, especially in aqueous solutions, but tetravalent berkelium compounds are also known. The existence of divalent berkelium salts is uncertain and has only been reported in mixed lanthanum chloride-strontium chloride melts. Aqueous solutions of Bk3+ ions are green in most acids. The color of the Bk4+ ions is yellow in hydrochloric acid and orange-yellow in sulfuric acid. Berkelium does not react rapidly with oxygen at room temperature, possibly due to the formation of a protective oxide surface layer; however, it reacts with molten metals, hydrogen, halogens, chalcogens and pnictogens to form various binary compounds. Berkelium can also form several organometallic compounds.

<span class="mw-page-title-main">Lead compounds</span> Type of compound

Compounds of lead exist with lead in two main oxidation states: +2 and +4. The former is more common. Inorganic lead(IV) compounds are typically strong oxidants or exist only in highly acidic solutions.

Lead ochre or lead ocher in American English (German: bleiocker; from Ancient Greek ὤχραōkhrós 'pale yellow, orange'), as well as plumbic ocher or lead oxide — at least three lead minerals (pigments) that resemble ocher in appearance. Under such a trivial name, minerals and pigments of cream, yellow, orange and red colours were known, reminiscent of or corresponding to the powdery consistency of ochre. The term ″lead ochre″ was used primarily among glassblowers, artisans, as well as geologists and miners. It may refer to:

References

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  2. "Lead compounds (as Pb)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  3. 1 2 Carr, Dodd S. (2005). "Lead Compounds". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a15_249. ISBN   978-3527306732.
  4. 1 2 Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 382–387. ISBN   978-0-08-037941-8.
  5. 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.
  6. 1 2 3 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.
  7. 1 2 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)
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  9. 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.
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  11. 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.
  12. "ICSD Entry: 94333". Cambridge Structural Database: Access Structures. Cambridge Crystallographic Data Centre . Retrieved 2021-06-01.
  13. Lead Processing @ Universalium.academic.ru. Alt address: Lead processing @ Enwiki.net.
  14. 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 ]
  15. Chapter 9, "Lead Compounds", in the book Ceramic and Glass Materials: Structure, Properties and Processing, published by Springer, year 2008.
  16. Compton, Kenneth (5 December 2003). Image Performance in CRT Displays. SPIE Press. ISBN   9780819441447 via Google Books.
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