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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 Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...
-based
reagent In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a ...
s. It also occurs naturally in the form of the mineral cotunnite.


Structure and properties

In solid PbCl2, each lead ion is coordinated by nine chloride ions in a tricapped triangular prism formation — six lie at the vertices of a triangular prism and three lie beyond the centers of each rectangular prism face. The 9 chloride ions are not equidistant from the central lead atom, 7 lie at 280–309 pm and 2 at 370 pm. PbCl2 forms white orthorhombic needles. In the gas phase, PbCl2 molecules have a bent structure with the Cl–Pb–Cl angle being 98° and each Pb–-Cl bond distance being 2.44 Å. Such PbCl2 is emitted from internal combustion engines that use ethylene chloride-
tetraethyllead Tetraethyllead (commonly styled tetraethyl lead), abbreviated TEL, is an organolead compound with the formula lead, Pb(ethyl group, C2H5)4. It was widely used as a fuel additive for much of the 20th century, first being mixed with gasoline begi ...
additives for antiknock purposes. PbCl2 is sparingly soluble in water, solubility product ''K''sp = at 20 °C. It is one of only 5 commonly water-insoluble chlorides, the other 4 being thallium(I) chloride,
silver chloride Silver chloride is an inorganic chemical compound with the chemical formula Ag Cl. This white crystalline solid is well known for its low solubility in water and its sensitivity to light. Upon illumination or heating, silver chloride converts ...
(AgCl) with ''K''sp = ,
copper(I) chloride Copper(I) chloride, commonly called cuprous chloride, is the lower chloride of copper, with the formula CuCl. The substance is a white solid sparingly soluble in water, but very soluble in concentrated hydrochloric acid. Impure samples appear gr ...
(CuCl) with ''K''sp = and mercury(I) chloride (Hg2Cl2) with ''K''sp = .


Synthesis

Solid lead(II) chloride
precipitate In an aqueous solution, precipitation is the "sedimentation of a solid material (a precipitate) from a liquid solution". The solid formed is called the precipitate. In case of an inorganic chemical reaction leading to precipitation, the chemic ...
s upon addition of aqueous
chloride The term chloride refers to a compound or molecule that contains either a chlorine anion (), which is a negatively charged chlorine atom, or a non-charged chlorine atom covalently bonded to the rest of the molecule by a single bond (). The pr ...
sources (HCl, NaCl, KCl) to aqueous solutions of
lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...
(II) compounds, such as lead(II) nitrate and lead(II) acetate: : It also forms by treatment of basic lead(II) compounds such as
Lead(II) oxide Lead(II) oxide, also called lead monoxide, is the inorganic compound with the molecular formula Pb O. It occurs in two polymorphs: litharge having a tetragonal crystal structure, and massicot having an orthorhombic crystal structure. Modern ...
and lead(II) carbonate. Lead dioxide is reduced by chloride as follows: : It also formed by the oxidation of lead metal by
copper(II) chloride Copper(II) chloride, also known as cupric chloride, is an inorganic compound with the chemical formula . The monoclinic crystal system, monoclinic yellowish-brown anhydrous form slowly absorbs moisture to form the orthorhombic blue-green hydrate, ...
: : Or most straightforwardly by the action of
chlorine Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between ...
gas on lead metal: :


Reactions

Addition of chloride ions to a suspension of PbCl2 gives rise to soluble
complex Complex commonly refers to: * Complexity, the behaviour of a system whose components interact in multiple ways so possible interactions are difficult to describe ** Complex system, a system composed of many components which may interact with each ...
ions. In these reactions the additional chloride (or other
ligand In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's el ...
s) break up the chloride bridges that comprise the polymeric framework of solid PbCl2(s). :PbCl2(s) + ClbCl3sup>−(aq) :PbCl2(s) + 2 ClbCl4sup>2−(aq) PbCl2 reacts with molten NaNO2 to give PbO: :PbCl2(l) + 3 NaNO2 → PbO + NaNO3 + 2 NO + 2 NaCl PbCl2 is used in synthesis of lead(IV) chloride (PbCl4): Cl2 is bubbled through a saturated solution of PbCl2 in aqueous NH4Cl forming H4sub>2 bCl6 The latter is reacted with cold concentrated
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, ...
(H2SO4) forming PbCl4 as an oil. Lead(II) chloride is the main precursor for
organometallic Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and so ...
derivatives of lead, such as plumbocenes. The usual alkylating agents are employed, including
Grignard reagent Grignard reagents or Grignard compounds are chemical compounds with the general formula , where X is a halogen and R is an organic group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride and phenylmagnesium bromi ...
s and organolithium compounds: :2 PbCl2 + 4 RLi → R4Pb + 4 LiCl + Pb :2 PbCl2 + 4 RMgBr → R4Pb + Pb + 4 MgBrCl :3 PbCl2 + 6 RMgBr → R3Pb-PbR3 + Pb + 6 MgBrCl These reactions produce derivatives that are more similar to organosilicon compounds, ''i.e.'' that Pb(II) tends to disproportionate upon alkylation. PbCl2 can be used to produce PbO2 by treating it with
sodium hypochlorite Sodium hypochlorite is an alkaline inorganic chemical compound with the formula (also written as NaClO). It is commonly known in a dilute aqueous solution as bleach or chlorine bleach. It is the sodium salt of hypochlorous acid, consisting of ...
(NaClO), forming a reddish-brown precipitate of PbO2.


Uses

*Molten PbCl2 is used in the synthesis of lead titanate and
barium Barium is a chemical element; it has symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element. Th ...
lead titanate ceramics by cation replacement reactions: *:''x'' PbCl2(l) + BaTiO3(s) → Ba1−''x''Pb''x''TiO3 + ''x'' BaCl2 *PbCl2 is used in production of infrared transmitting glass,Dictionary of Inorganic and Organometallic Compounds. ''Lead(II) Chloride.

/ref> and ornamental glass called aurene glass. Aurene glass has an iridescent surface formed by spraying with PbCl2 and reheating under controlled conditions. Stannous chloride (SnCl2) is used for the same purpose. *Pb is used in HCl service even though the PbCl2 formed is slightly soluble in HCl. Addition of 6–25% of
antimony Antimony is a chemical element; it has chemical symbol, symbol Sb () and atomic number 51. A lustrous grey metal or metalloid, it is found in nature mainly as the sulfide mineral stibnite (). Antimony compounds have been known since ancient t ...
(Sb) increases corrosion resistance. *A basic chloride of lead, PbCl2·Pb(OH)2, is known as Pattinson's white lead and is used as pigment in white paint.
Lead paint Lead paint or lead-based paint is paint containing lead. As pigment, lead(II) chromate (, "chrome yellow"), lead(II,IV) oxide, (, "red lead"), and lead(II) carbonate (, "white lead") are the most common forms.. Lead is added to paint to acceler ...
is now banned as a health hazard in many countries by the White Lead (Painting) Convention, 1921. *PbCl2 is an intermediate in refining
bismuth Bismuth is a chemical element; it has symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs nat ...
(Bi) ore. The ore containing Bi, Pb, and Zn is first treated with molten caustic soda to remove traces of
arsenic Arsenic is a chemical element; it has Symbol (chemistry), symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is not ...
and
tellurium Tellurium is a chemical element; it has symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally fou ...
. This is followed by the
Parkes process The Parkes process is a pyrometallurgical industrial process for removing silver from lead during the production of bullion. It is an example of liquid–liquid extraction. The process takes advantage of two liquid-state properties of zinc. The fi ...
to remove any silver and gold present. There are now Bi, Pb, and Zn in the ore. At 500 °C, it receives treatment from Cl2 gas. First, ZnCl2 forms and is excreted. Pure Bi is left behind after PbCl2 forms and is eliminated. Lastly, BiCl3 would form.Kirk-Othmer. ''Encyclopedia of Chemical Technology''. (ed 4). p. 241


Toxicity

Like other soluble lead compounds, exposure to PbCl2 may cause
lead poisoning Lead poisoning, also known as plumbism and saturnism, is a type of metal poisoning caused by lead in the body. Symptoms may include abdominal pain, constipation, headaches, irritability, memory problems, infertility, numbness and paresthesia, t ...
.


References


External links


IARC Monograph: "Lead and Lead Compounds"




* ttps://www.atsdr.cdc.gov/csem/csem.html Case Studies in Environmental Medicine – Lead Toxicity
ToxFAQs: Lead
{{Chlorides Lead(II) compounds Chlorides Metal halides IARC Group 2A carcinogens