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Lead(II) oxide

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Lead(II) oxide
Names
IUPAC name Lead(II) oxide
Other names Lead monoxide
Litharge
Massicot
Plumbous oxide
Identifiers
CAS Number
ECHA InfoCard 100.013.880 Edit this at Wikidata
RTECS number
  • OG1750000
UN number 3288
CompTox Dashboard (EPA)
Properties
Chemical formula PbO
Molar mass 223.20 g/mol
Appearance red or yellow powder
Density 9.64 g/cm
Melting point 888 °C (1,630 °F; 1,161 K)
Boiling point 1,477 °C (2,691 °F; 1,750 K)
Solubility in water insoluble
Solubility insoluble in dilute alkalis
soluble in concentrated alkalis
soluble in HCl
Structure
Crystal structure tetragonal, tP4
Space group P4/nmm, No. 129
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 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
Related compounds
Other anions Lead sulfide
Lead selenide
Lead telluride
Other cations Carbon monoxide
Silicon monoxide
Tin(II) oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). checkY verify (what is  ?) Infobox references
Chemical compound

Lead(II) oxide is the inorganic compound with the formula PbO. Lead(II) oxide occurs in two polymorphs, red, having a tetragonal crystal structure and yellow, having an orthorhombic crystal structure. Both forms occur naturally as rare minerals: the red form is known as litharge and the yellow form is known as massicot.

Preparation and structure

PbO may be prepared by heating lead metal in air at approx. 600 °C. At this temperature it is also the end product of oxidation of other lead oxides in air:

PbO2 –(293 °C)→ Pb12O19 –(351 °C)→ Pb12O17 –(375 °C)→ Pb3O4 –(605 °C)→ PbO

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

2 Pb(NO3)2 → 2 PbO + 4 NO2 + O2
PbCO3 → PbO + CO2

As determined by X-ray crystallography, the compound features pyramidal four-coordinate Pb center. The pyramidal nature indicates the presence of a stereo-chemically active lone pair of electrons.

Reactions

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 Pb via the intermediacy of oxo clusters such as . With strong base, PbO dissolves to form plumbite(II) salts: PbO + H2O + OH →

Applications

PbO is produced on a large scale as an intermediate in the conversion of lead ores, mainly galena into metallic lead. The consumption of lead, and hence the processing of PbO, correlates with the number of automobiles because it remains the key component of automotive lead-acid batteries.

PbO is used extensively in manufacturing of lead glasses and ceramic glazes as well as in fine dinnerware. For such applications, the PbO is converted in situ to lead silicate, which is less toxic. Other less dominating applications include the vulcanization of rubber and the production of certain pigments and paints. PbO is used in cathode ray tube glass to block X-ray emission, but mainly in the neck and funnel because it can cause discoloration when used in the faceplate. Strontium oxide is preferred for the faceplate.


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 aquaria, and was also once used to seal glass panels in window frames. It is a component of lead paints.

PbO is used in certain condensation reactions in organic synthesis.

Health issues

Main article: Lead poisoning

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

References

  1. Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0070494398
  2. ^ 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
  3. N.N. Greenwood, A. Earnshaw, "Chemistry of Elements", 2nd edition, Butterworth-Heinemann, 1997.
  4. Wells, A. F. (1984), Structural Inorganic Chemistry (5th ed.), Oxford: Clarendon Press, ISBN 0-19-855370-6
  5. Charles A. Sutherland, Edward F. Milner, Robert C. Kerby, Herbert Teindl, Albert Melin, Hermann M. Bolt “Lead” in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a15_193.pub2
  6. Dodd S. Carr "Lead Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinhiem. doi:10.1002/14356007.a15_249
  7. Corson, B. B. (1936). "1,4-Diphenylbutadiene". Organic Syntheses. 16: 28; Collected Volumes, vol. 2, p. 229.
  8. "Lead (II) oxide". International Occupational Safety and Health Information Centre. Retrieved 2009-06-06.

External links

Lead compounds
Pb(II)
Pb(II,IV)
Pb(IV)
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