Lead(II) chloride 1144596 224110286 2008-07-07T10:34:54Z Psymier 6066981 /* Precipitation from aqueous solution */ <!--redirects here: lead (II) chloride, lead dichloride, lead chloride, plumbous chloride, pbcl2--> {{Chembox new | Name = Lead(II) chloride | ImageFile = Lead(II) chloride.jpg | ImageName = Lead(II) chloride | ImageFile1 = Cotunnite-3D-ionic.png | ImageName1 = Cotunnite crystal structure | OtherNames = Plumbous chloride<br />Cotunnite | Section1 = {{Chembox Identifiers | CASNo = 7758-95-4 }} | Section2 = {{Chembox Properties | Formula = PbCl<sub>2</sub> | MolarMass = 278.10 g/mol | Appearance = white odorless solid | Density = 5.85 g/cm<sup>3</sup>, solid | Solubility = 0.99 g/100 mL (20 °C) | MeltingPt = 501 °C | BoilingPt = 950 °C }} | Section4 = {{Chembox Thermochemistry | DeltaHf = -359.41 kJ/mol | Entropy = 135.98 J.K<sup>−1</sup>.mol<sup>−1</sup> }} | Section7 = {{Chembox Hazards | EUClass = Toxic ('''T''')<br />Repr. Cat. 1/3<br />Dangerous for<br />the environment ('''N''') | RPhrases = {{R61}}, {{R20/22}}, {{R33}}, {{R62}}, {{R50/53}} | SPhrases = {{S53}}, {{S45}}, {{S60}}, {{S61}} }} | Section8 = {{Chembox Related | OtherAnions = [[Lead(II) fluoride]]<br />[[Lead(II) bromide]]<br />[[Lead(II) iodide]] | OtherCations = [[Lead(IV) chloride]]<br />[[Tin(II) chloride]] }} }} '''Lead(II) chloride''' has the formula '''PbCl<sub>2</sub>'''. It is also known as '''lead chloride''', '''lead dichloride''', and '''plumbous chloride'''. PbCl<sub>2</sub> is one of the most important lead-based [[reagent]]s. PbCl<sub>2</sub> also occurs naturally in the form of the mineral cotunnite. ==Solubility== The [[solubility]] of PbCl<sub>2</sub> in water is low (9.9 g/L at 20 °C) and for practical purposes it is considered insoluble. Its [[solubility-product constant]] (K<sub>sp</sub>) at 25 °C (298 K) is 1.6 x 10<sup>-5</sup>. It is one of only three commonly insoluble chlorides, the other two being [[silver chloride]] (AgCl) with K<sub>sp</sub> = 1.8 x 10<sup>-10</sup> and [[mercury (I) chloride]] (Hg<sub>2</sub>Cl<sub>2</sub>) with K<sub>sp</sub> = 1.3 x 10<sup>-18</sup>.<ref>Brown, Lemay, Burnsten. "Chemistry The Central Science". ''Solubility-Product Constants for Compounds at 25<sup>o</sup>C.'' (ed 6, 1994). p 1017</ref> ==Reactions== ===Precipitation from aqueous solution=== Lead(II) chloride [[precipitate]]s from solution upon addition of [[chloride]] sources (HCl, NaCl, KCl) to aqueous solutions of [[lead]](II) compounds such as [[lead(II) nitrate|Pb(NO<sub>3</sub>)<sub>2</sub>]]. :Pb(NO<sub>3</sub>)<sub>2(aq)</sub> + 2 [[Sodium chloride|NaCl]]<sub>(aq)</sub> → PbCl<sub>2(s)</sub> + 2 [[Sodium nitrate|NaNO<sub>3</sub>]]<sub>(aq)</sub> :[[Lead(II) acetate|Pb(CH<sub>3</sub>COO)<sub>2</sub>]]<sub>(aq)</sub> + [[Hydrochloric acid|HCl]]<sub>(aq)</sub> → PbCl<sub>2(s)</sub> + 2 [[Acetic acid|CH<sub>3</sub>COOH]]<sub>(aq)</sub> :basic [[Lead(II) carbonate|PbCO<sub>3</sub>]] + 2 HCl<sub>(aq)</sub> → PbCl<sub>2(s)</sub> + CO<sub>2(g)</sub> + H<sub>2</sub>O<ref>Dictionary of Inorganic and Organometallic Compounds. ''Lead(II) Chloride.'' [http://www.chemnetbase.com]</ref> :Pb(NO<sub>3</sub>)<sub>2(aq)</sub> + 2HCl<sub>(aq)</sub> → PbCl<sub>2(s)</sub> + 2HNO<sub>3(aq)</sub> ===Soluble chloro complexes=== Addition of chloride ions to a suspension of PbCl<sub>2</sub> gives rise to soluble [[Complex (chemistry)|complex]] ions. In these reactions the additional chloride (or other [[ligand]]s) break up the chloride bridges that comprise the polymeric framework of solid PbCl<sub>2(s)</sub>. :PbCl<sub>2(s)</sub> + [[Chloride|Cl<sup>-</sup>]] → [PbCl<sub>3</sub>]<sup>-</sup><sub>(aq)</sub> [PbCl<sub>3</sub>]<sup>-</sup><sub>(aq)</sub> is [[isoelectronic]] with PCl<sub>3</sub>. :PbCl<sub>2(s)</sub> + 2 Cl<sup>-</sup> → [PbCl<sub>4</sub>]<sup>2-</sup><sub>(aq)</sub> ===Organometallic derivatives=== Lead(II) chloride is the main [[wiktionary:Precursor|precursor]] for [[organometallic]] derivatives of lead. The usual alkylating agents are employed, including [[grignard reagent]]s and organolithium compounds: :2 PbCl<sub>2</sub> + 4 RLi → R<sub>4</sub>Pb + 4 LiCl + Pb :2 PbCl<sub>2</sub> + 4 RMgBr → R<sub>4</sub>Pb + Pb + 4 MgBrCl :3 PbCl<sub>2</sub> + 6 RMgBr → R<sub>3</sub>Pb-PbR<sub>3</sub> + Pb + 6 MgBrCl<ref>Housecroft & Sharpe. "Inorganic Chemistry". (ed 2, 2005). p 524</ref> Notice how these reactions produce derivatives that are more similar to organosilicon compounds, ''i.e.'' that Pb(II) tends to disproportionate upon alkylation. ===Conversion to oxides=== PbCl<sub>2</sub> reacts with molten [[sodium nitrite|NaNO<sub>2</sub>]] to give PbO: :PbCl<sub>2(l)</sub> + 3 NaNO<sub>2</sub> → PbO + NaNO<sub>3</sub> + 2NO + 2 NaCl PbCl<sub>2</sub> is also used to prepare ceramics by cation replacement reactions: :xPbCl<sub>2(l)</sub> + BaTiO<sub>3(s)</sub> → Ba<sub>1-x</sub>Pb<sub>x</sub>TiO<sub>3</sub> + xBaCl<sub>2</sub><ref>Aboujalil, A. et al., "Molten salt synthesis of the lead titanate PbTiO3, investigation of the reactivity of various titanium and lead salts with molten alkali-metal nitrites", ''J. Mater. Chem.'', 1998, '''8''', 1601&ndash;1606</ref> ==Synthesis== PbCl<sub>2</sub> can be synthesized by several methods as discussed above, that is, by precipitation as a solid by reaction of an aqueous Pb(II) salts with a soluble chloride salts. An interesting reaction involves treatment of Pb(IV) oxide with HCl: :[[Lead dioxide|PbO<sub>2]](s)</sub> + 4 HCl → PbCl<sub>2(s)</sub> + [[Chlorine|Cl<sub>2</sub>]] + 2 H<sub>2</sub>O Notice that lead(IV) chloride is not formed as it is unstable with respect to loss of Cl<sub>2</sub>. PbCl<sub>2(s)</sub> also forms by the action of [[chlorine]] gas on Pb metal: :[[Lead|Pb]] + Cl<sub>2</sub> → PbCl<sub>2</sub> ==Uses of lead(II) chloride== *Molten PbCl<sub>2</sub> is used in the synthesis of lead titanate (PbTiO<sub>3</sub>) and [[barium]] lead titanate (see reaction above).<ref>Aboujalil, A. et al., "Molten salt synthesis of the lead titanate PbTiO3, investigation of the reactivity of various titanium and lead salts with molten alkali-metal nitrites", ''J. Mater. Chem.'', 1998, '''8''', 1601&ndash;1606</ref> *PbCl<sub>2</sub> is used in organometallic synthesis to make [[metallocene]]s, known as [[plumbocene]]s.<ref>Lowack, R.H. et al., "Decasubstituted decaphenylmetallocenes", ''J. Organomet. Chem.'', 1994, '''476''', 25-32</ref> It is also used to make compounds of the formula R<sub>4</sub>Pb from [[Grignard reagents]] or organo-lithium compounds (see organometallic reactions above).<ref>Housecroft & Sharpe. "Inorganic Chemistry". (ed 2, 2005). p 524</ref> *PbCl<sub>2</sub> is used in production of infrared transmitting glass.<ref>Dictionary of Inorganic and Organometallic Compounds. ''Lead(II) Chloride.'' [http://www.chemnetbase.com]</ref> *PbCl<sub>2</sub> is used in production of ornamental glass called [[aurene glass]]. This stained glass has an iridescent surface formed by spraying with PbCl<sub>2</sub> and reheating under controlled conditions. [[Stannous chloride]] (SnCl<sub>2</sub>) is used for the same purpose.<ref>Stained Glass Terms and Definitions. ''aurene glass''. [http://www.thestorefinder.com/glass/library/terms/termsA.html]</ref> *PbCl<sub>2</sub> is used in synthesis of lead(IV) chloride (PbCl<sub>4</sub>): Cl<sub>2</sub> is bubbled through a saturated solution of PbCl<sub>2</sub> in aqueous NH<sub>4</sub> forming [NH<sub>4</sub>]<sub>2</sub>[PbCl<sub>6</sub>]. The latter is reacted with cold concentrated [[sulfuric acid]] (H<sub>2</sub>SO<sub>4</sub>) forming PbCl<sub>4</sub> as an oil.<ref>Housecroft & Sharpe. "Inorganic Chemistry". (ed 2, 2005). p 365</ref> *Pb is used in HCl service even though the PbCl<sub>2</sub> formed is slightly soluble in HCl. Addition of 6-25% of [[antimony]] (Sb) increases corrosion resistance.<ref>Kirk-Othmer. "Encyclopedia of Chemical Technology". (ed 4). p 913</ref> *A basic chloride of lead, PbCl<sub>2</sub>·Pb(OH)<sub>2</sub>, is known as Patteson's white lead and is used as pigment in white paint.<ref>Perry & Phillips. "Handbook of Inorganic Compounds". (1995). p 213</ref> *PbCl<sub>2</sub> is an intermediate in refining [[bismuth]] (Bi) ore. The ore containing Bi, Pb, and Zn is first treated with molten [[caustic soda]] to remove traces of acidic elements such as [[arsenic]] and [[tellurium]]. This is followed by the Parkes desilverization process to remove any silver and gold present. The ore now contains Bi, Pb, and Zn. It is treated with Cl<sub>2</sub> gas at 500 °C. ZnCl<sub>2</sub> forms first and is removed. Then PbCl<sub>2</sub> forms and is removed leaving pure Bi. BiCl<sub>2</sub> would form last.<ref>Kirk-Othmer. "Encyclopedia of Chemical Technology". (ed 4). p 241</ref> ==Structure== [[Image:Cotunnite-3D-balls.png|thumb|right|250px|[[Crystal structure]] of connutite, PbCl<sub>2</sub>]] In solid PbCl<sub>2</sub>, each lead is coordinated by 9 chloride ions - 6 lie at the apices of a trigonal prism and 3 lie beyond the centers of each prism face. The 9 chloride ions are not equidistant from the central lead atom, 7 lie between 280-309 pm and 2 are at 370pm.<ref> Wells A.F. (1984) ''Structural Inorganic Chemistry'' 5th edition Oxford Science Publications ISBN 0-19-855370-6 </ref> PbCl<sub>2</sub> forms white orthorhombic needles. Vaporized PbCl<sub>2</sub> molecules have a bent structure with the Cl-Pb-Cl angle being 98° and each Pb-Cl bond distance being 2.44Å.<ref>Hargittai, I. et al.,"Two independent gas electron diffraction investigations of the structure of plumbous chloride", ''J. Mol. Struct.'', 1977, '''42''', 147</ref> PbCl<sub>2</sub> is emitted from internal combustion engines that use ethylene chloride-[[tetraethyllead]] additives for antiknock purposes. ==Cotunnite== PbCl<sub>2</sub> occurs naturally in the form of the mineral cotunnite. It is colorless, white, yellow, or green with a density of 5.3-5.8 g/cm<sup>3</sup>. The hardness on the [[Mohs hardness|Mohs scale]] is 1.5-2. The crystal structure is orthorhombic dipyramidal and the point group is 2/m 2/m 2/m. Each Pb has a coordination number of 9. The composition is 74.50% Pb and 25.50% Cl. Cotunnite occurs near volcanoes: Vesuvius, Italy; Tarapaca, Chile; and Tolbachik, Russia.<ref>Cotunnite [http://webmineral.com/data/Cotunnite.shtml]</ref> <!--It would be helpful if a geologist looked at that page because the terms are foreign to me--> <!--also, conflicting data w/ the following page (ie: hardness): http://rruff.geo.arizona.edu/doclib/hom/cotunnite.pdf--> ==Toxicity== Like other lead containing compounds, exposure to PbCl<sub>2</sub> may cause [[lead poisoning]]. ==References== <references /> </div> ==External links== * [http://www-cie.iarc.fr/htdocs/monographs/suppl7/leadandleadcompounds.html IARC Monograph: "Lead and Lead Compounds"] * [http://www-cie.iarc.fr/htdocs/announcements/vol87.htm IARC Monograph: "Inorganic and Organic Lead Compounds"] * [http://www.npi.gov.au/database/substance-info/profiles/50.html National Pollutant Inventory - Lead and Lead Compounds Fact Sheet] * [http://www.atsdr.cdc.gov/HEC/CSEM/lead/ Case Studies in Environmental Medicine - Lead Toxicity] * [http://www.atsdr.cdc.gov/tfacts13.html ToxFAQs: Lead] [[Category:Lead compounds]] [[Category:Chlorides]] [[Category:Metal halides]] [[Category:IARC Group 2A carcinogens]] [[ar:كلوريد رصاص ثنائي]] [[de:Blei(II)-chlorid]] [[it:Cloruro di piombo]] [[ja:塩化鉛]] [[pl:Chlorek ołowiu(II)]]