Lead(IV) chloride
Lead tetrachloride contaminated with lead(II) chloride
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Names | |
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IUPAC name
Lead(IV) chloride
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Systematic IUPAC name
Tetrachloroplumbane | |
Identifiers | |
3D model (
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ChemSpider | |
PubChem CID
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CompTox Dashboard (EPA)
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Properties | |
PbCl4 | |
Molar mass | 349.012 g/mol[1] |
Appearance | yellow oily liquid[2] |
Density | 3.2 g⋅cm−3[1] |
Melting point | −15 °C (5 °F; 258 K)[1] stable below 0 °C (32 °F; 273 K)[2] |
Boiling point | 50 °C (122 °F; 323 K)[1] decomposes |
Reacts | |
Solubility | hydrochloric acid |
Structure | |
4 | |
tetrahedral[3] | |
Thermochemistry | |
Std enthalpy of (ΔfH⦵298)formation |
-328.9 kJ/mol |
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 tetrachloride, also known as lead(IV) chloride, has the molecular formula PbCl4. It is a yellow, oily liquid which is stable below 0 °C, and decomposes at 50 °C.[2] It has a tetrahedral configuration, with lead as the central atom. The Pb–Cl covalent bonds have been measured to be 247 pm and the bond energy is 243 kJ⋅mol−1.[4]
Synthesis
Lead tetrachloride can be made by reacting lead(II) chloride PbCl2, and hydrochloric acid HCl, in the presence of chlorine gas (Cl2),[5] leading to the formation of chloroplumbic acid H2PbCl6. It is then converted to the ammonium salt (NH4)2PbCl6 by adding ammonium chloride (NH4Cl). Finally, the solution is treated with concentrated sulfuric acid H2SO4, to separate out lead tetrachloride. This series of reactions is conducted at 0 °C. The following equations illustrate the reaction:
- PbCl2 + 2HCl + Cl2 → H2PbCl6
- H2PbCl6 + 2 NH4Cl → (NH4)2PbCl6 + 2HCl
- (NH4)2PbCl6 + H2SO4 → PbCl4+ 2HCl + (NH4)2SO4
Reaction with water
Unlike
- PbCl4 + 2H2O → PbO2(s) + 4HCl(g)
Stability
Lead tetrachloride tends to
- PbCl4 → PbCl2 + Cl2(g)
There are reports that this reaction can proceed explosively and that the compound is best stored under pure sulfuric acid at -80 °C in the dark.[6]
The stability of the +4
Toxicity
Lead is a
References
- ^ a b c d "Lead compounds: Lead Tetrachloride". WebElements.com. Retrieved 10 October 2012.
- ^ ISBN 978-0-08-037941-8.
- ^ a b c d "The Chlorides of Carbon, Silicon and Lead". chemguide.co.uk. Retrieved 10 October 2012.
- ^ ISBN 978-0-19-855819-4.
- PMID 18891892.
- ISBN 9781483187587
- ISBN 978-0-13-612866-3.
- ^ National Toxicology Program, Department of Health and Human Services (2011). Report on Carcinogens, Twelfth Edition (2011) - Lead and Lead Compounds (PDF). p. 251.
- ^ "Environmental Health & Safety - 1: General Information About Chemical Safety". Princeton UNiversity. Archived from the original on 27 April 2013. Retrieved 11 October 2012.