Lead(II) sulfide

Lead(II) sulfide
Names
Other names
Plumbous sulfide
Galena, Sulphuret of lead
Identifiers
1314-87-0 YesY
ChemSpider 14135 N
Jmol interactive 3D Image
Properties
PbS
Molar mass 239.30 g/mol
Density 7.60 g/cm3[1]
Melting point 1,118 °C (2,044 °F; 1,391 K)
Boiling point 1,281 °C (2,338 °F; 1,554 K)
2.6×10−11 kg/kg (calculated, at pH=7)[2] 8.6×10−7 kg/kg[3]
9.04×10−29
3.91
Structure
Halite (cubic), cF8
Fm3m, No. 225
a = 5.936 Angstroms [4]
Octahedral (Pb2+)
Octahedral (S2−)
Thermochemistry
46.02 J/degree mol
91.3 J/mol
–98.7 kJ/mol
Hazards
Safety data sheet External MSDS
Repr. Cat. 1/3
Harmful (Xn)
Dangerous for the environment (N)
R-phrases R61, R20/22, R33, R62, R50/53
S-phrases S53, S45, S60, S61
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
0
2
0
Flash point Non-flammable
Related compounds
Other anions
 Lead(II) oxide
Lead selenide
Lead telluride
Other cations
 Carbon monosulfide
Silicon monosulfide
Germanium(II) sulfide
Tin(II) sulfide
Related compounds
 Thallium sulfide
Lead(IV) sulfide
Bismuth sulfide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

Lead(II) sulfide (also spelled sulphide) is an inorganic compound with the formula PbS. PbS, also known as galena, is the principal ore, and most important compound of lead. It is a semiconducting material with niche uses.

Formation, basic properties, related materials

Addition of hydrogen sulfide or sulfide salts to a solution of lead ions gives PbS as an insoluble black precipitate.

Pb2+ + H2S → PbS + 2 H+

The equilibrium constant for this reaction is 3×106 M.[5] This reaction, which entails a dramatic color change from colourless or white to black, was once used in qualitative inorganic analysis. The presence of hydrogen sulfide or sulfide ions is still routinely tested using "lead acetate paper."

Like the related materials PbSe and PbTe, PbS is a semiconductor.[6] In fact, lead sulfide was one of the earliest materials to be used as a semiconductor.[7] Lead sulfide crystallizes in the sodium chloride motif, unlike many other IV-VI semiconductors.

Since PbS is the main ore of lead, much effort has focused on its conversion. A major process involves smelting of PbS followed by reduction of the resulting oxide. Idealized equations for these two steps are:[8]

2 PbS + 3 O2 → 2 PbO + 2 SO2
PbO + C → Pb + CO

The sulfur dioxide is converted to sulfuric acid.

Nanoparticles

Lead sulfide-containing nanoparticle and quantum dots have been well studied.[9] Traditionally, such materials are produced by combining lead salts with a variety of sulfide sources.[10][11] PbS nanoparticles have been recent examined for use in solar cells.[12]

Applications

PbS was once used as a black pigment, but current applications exploit its semiconductor properties, which have long been recognized.[13]

Infrared sensor (Photoconductor)

PbS is one of the oldest and most common detection element materials in various infrared detectors. As an infrared detector, PbS functions as a photon detector, responding directly to the photons of radiation, as opposed to thermal detectors, which respond to a change in detector element temperature caused by the radiation. A PbS element can be used to measure radiation in either of two ways: by measuring the tiny photocurrent the photons cause when they hit the PbS material, or by measuring the change in the material's electrical resistance that the photons cause. Measuring the resistance change is the more commonly used method. At room temperature, PbS is sensitive to radiation at wavelengths between approximately 1 and 2.5 μm. This range corresponds to the shorter wavelengths in the infra-red portion of the spectrum, the so-called short-wavelength infrared (SWIR). Only very hot objects emit radiation in these wavelengths.

Cooling the PbS elements, for example using liquid nitrogen or a Peltier element system, shifts its sensitivity range to between approximately 2 and 4 μm. Objects that emit radiation in these wavelengths still have to be quite hot—several hundred degrees Celsius—but not as hot as those detectable by uncooled sensors. (Other compounds used for this purpose include indium antimonide (InSb) and mercury-cadmium telluride (HgCdTe), which have somewhat better properties for detecting the longer IR wavelengths.) The high dielectric constant of PbS leads to relatively slow detectors (compared to silicon, germanium, InSb, or HgCdTe).

Astronomy

Elevations above 2.6 km (1.63 mi) on the planet Venus are coated with a shiny substance. Though the composition of this coat is not entirely certain, one theory is that Venus "snows" crystallized lead sulfide much as Earth snows frozen water. If this is the case, it would be the first time the substance was identified on a foreign planet. Other less likely candidates for Venus' "snow" are bismuth sulfide and tellurium.[14]

Safety

Lead(II) sulfide is so insoluble that it is almost nontoxic, but pyrolysis of the material, as in smelting, gives dangerous fumes.[15] Lead sulfide is insoluble and a stable compound in the pH of blood and so is probably one of the less toxic forms of lead.[16] A large safety risk occurs in the synthesis of PbS using lead carboxylates, as they are particularly soluble and can cause negative physiological conditions.

References

  1. ↑ Patnaik, Pradyot (2003). Handbook of Inorganic Chemical Compounds. McGraw-Hill. ISBN 0-07-049439-8. Retrieved 2009-06-06.
  2. ↑ W. Linke (1965). Solubilities. Inorganic and Metal-Organic Compounds 2. Washington, D.C.: American Chemical Society. p. 1318.
  3. ↑ Ronald Eisler (2000). Handbook of Chemical Risk Assessment. CRC Press. ISBN 1-56670-506-1.
  4. ↑ http://www.springermaterials.com/docs/pdf/10681727_889.html
  5. ↑ Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
  6. ↑ Vaughan, D. J.; Craig, J. R. (1978). Mineral Chemistry of Metal Sulfides. Cambridge: Cambridge University Press. ISBN 0-521-21489-0.;
  7. ↑ C.Michael Hogan. 2011. Sulfur. Encyclopedia of Earth, eds. A.Jorgensen and C.J.Cleveland, National Council for Science and the environment, Washington DC
  8. ↑ Charles A. Sutherland, Edward F. Milner, Robert C. Kerby, Herbert Teindl, Albert Melin, Hermann M. Bolt (2005). Lead. in Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a15_193.pub2.
  9. ↑ "The Quantum Mechanics of Larger Semiconductor Clusters ("Quantum Dots")". Annual Review of Physical Chemistry 41 (1): 477–496. 1990-01-01. doi:10.1146/annurev.pc.41.100190.002401.
  10. ↑ Zhou, H. S.; Honma, I.; Komiyama, H.; Haus, Joseph W. (2002-05-01). "Coated semiconductor nanoparticles; the cadmium sulfide/lead sulfide system's synthesis and properties". The Journal of Physical Chemistry 97 (4): 895–901. doi:10.1021/j100106a015.
  11. ↑ Wang, Wenzhong; Liu, Yingkai; Zhan, Yongjie; Zheng, Changlin; Wang, Guanghou (2001-09-15). "A novel and simple one-step solid-state reaction for the synthesis of PbS nanoparticles in the presence of a suitable surfactant". Materials Research Bulletin 36 (11): 1977–1984. doi:10.1016/S0025-5408(01)00678-X.
  12. ↑ Lee, HyoJoong; Leventis, Henry C.; Moon, Soo-Jin; Chen, Peter; Ito, Seigo; Haque, Saif A.; Torres, Tomas; Nüesch, Frank; Geiger, Thomas (2009-09-09). "PbS and CdS Quantum Dot-Sensitized Solid-State Solar Cells: “Old Concepts, New Results”". Advanced Functional Materials 19 (17): 2735–2742. doi:10.1002/adfm.200900081. ISSN 1616-3028.
  13. ↑ Putley, E H; Arthur, J B (1951). "Lead Sulphide – An Intrinsic Semiconductor". Proceedings of the Physical Society. Series B 64: 616. doi:10.1088/0370-1301/64/7/110.
  14. ↑ "'Heavy metal' snow on Venus is lead sulfide". Washington University in St. Louis. Retrieved 2009-07-07.
  15. ↑ Lead sulfide MSDS
  16. ↑ Fritz Bischoff, L. C. Maxwell, Richard D. Evens and Franklin R. Nuzum (1928). "Studies on the Toxicity of Various Lead Compounds Given Intravenously". Journal of Pharmacology and Experimental Therapeutics 34 (1): 85–109.

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