Lead chlorides

The solid is essentially ionic, made up of Pb and Cl ions. The vapour contains bent molecules of PbCh (cf. SnCh). Lead chloride is precipitated when hydrochloric acid (or a solution of a chloride) is added to a cold solution of a lead(ll) salt. It dissolves in hot water but on cooling, is slowly precipitated in crystalline form. It dissolves in excess of concentrated hydrochloric acid to give the acid H2[Pb"Cl4]. 

A precipitation reaction occurs when two or more soluble species combine to form an insoluble product that we call a precipitate. The most common precipitation reaction is a metathesis reaction, in which two soluble ionic compounds exchange parts. When a solution of lead nitrate is added to a solution of potassium chloride, for example, a precipitate of lead chloride forms. We usually write the balanced reaction as a net ionic equation, in which only the precipitate and those ions involved in the reaction are included. Thus, the precipitation of PbCl2 is written as... 

T. C. Ho and co-workers, "Metal Capture During Fluidized Bed Incineration of Wastes Contaminated with Lead Chloride," presented at the... 

Ultimately, as the stabilization reactions continue, the metallic salts or soaps are depleted and the by-product metal chlorides result. These metal chlorides are potential Lewis acid catalysts and can greatiy accelerate the undesired dehydrochlorination of PVC. Both zinc chloride and cadmium chloride are particularly strong Lewis acids compared to the weakly acidic organotin chlorides and lead chlorides. This significant complication is effectively dealt with in commercial practice by the co-addition of alkaline-earth soaps or salts, such as calcium stearate or barium stearate, ie, by the use of mixed metal stabilizers. 

Although lead chloride is moderately soluble in the acid, lead is also used occasionaUy in hydrochloric acid service. Addition of 6—25% Sb increases the corrosion resistance. AH and ferric chloride accelerate the corrosion. Durichlor (14.5% Si, 3% Mo, 82% Fe), a sUica-based aUoy, shows exceUent resistance to hot hydrochloric acid in the absence of ferric chloride. 

Lead Chloride. Lead dichloride, PbCl2, forms white, orthorhombic needles some physical properties are given in Table 1. Lead chloride is slightly soluble in dilute hydrochloric acid and ammonia and insoluble in alcohol. It is prepared by the reaction of lead monoxide or basic lead carbonate with hydrochloric acid, or by treating a solution of lead acetate with hydrochloric acid and allowing the precipitate to settle. It easily forms basic chlorides, such as PbCl Pb(OH)2 [15887-88 ] which is known as Pattinson s lead white, an artist s pigment. 

Qualitative. The classic method for the quaUtative determination of silver ia solution is precipitation as silver chloride with dilute nitric acid and chloride ion. The silver chloride can be differentiated from lead or mercurous chlorides, which also may precipitate, by the fact that lead chloride is soluble ia hot water but not ia ammonium hydroxide, whereas mercurous chloride turns black ia ammonium hydroxide. Silver chloride dissolves ia ammonium hydroxide because of the formation of soluble silver—ammonia complexes. A number of selective spot tests (24) iaclude reactions with /)-dimethy1amino-henz1idenerhodanine, ceric ammonium nitrate, or bromopyrogaHol red [16574-43-9]. Silver is detected by x-ray fluorescence and arc-emission spectrometry. Two sensitive arc-emission lines for silver occur at 328.1 and 338.3 nm. 

This bismuth—calcium—magnesium dross also contains lead that must be removed. The dross is heated in a ketde to free any entrapped lead that melts and forms a pool under the dross. This lead is cast and returned to the bismuth separation cycle. The dross is then melted and treated with chlorine and/or lead chloride to remove the calcium and magnesium. The resulting molten metal is an alloy of bismuth and lead, high in bismuth which is then treated to produce refined bismuth metal. 

The desilverized alloy now contains bismuth as well as lead and ziac. To remove the lead and ziac, advantage is taken of the fact that ziac and lead chlorides are formed before bismuth chloride [7787-60-2J, BiCl, when the alloy is treated at 500°C with chlorine gas. Ziac chloride [7646-85-7] ZnCl, forms first, and after its removal lead chloride [7758-95-4], PbCl2, forms preferentially. This process is continued until the desired level of lead removal has been reached. The bismuth is given a final oxidation with air and caustic soda the refined product has a purity of 99.999%. 

The removal of silver from lead is accomplished by die addition of zinc to the molten lead, and slowly cooling to a temperature just above the melting point of lead (600 K). A crust of zinc containing the silver can be separated from the liquid, and the zinc can be removed from tlris product by distillation. The residual zinc in the lead can be removed eitlrer by distillation of the zinc, or by pumping chlorine tluough the metal to form a zinc-lead chloride slag. 

The most important class of stabilisers are the lead compounds which form lead chloride on reaction with hydrogen chloride evolved during decomposition. As a class the lead compounds give rise to products of varying opacity, are toxic and turn black in the presence of certain sulphur-containing compounds but are good heat stabilisers. 

Lead chloride is freely soluble in hot aqueous solutions, but lead fluoride is almost insoluble in dilute HE solutions. When the HE concentration reaches about 40%, steel is preferred. 

Latin American Crop Protection Association (LACPA), 259 Latvian histihite of Organic Synthesis (OIS), 262 Latvian Ministry of Eiivironmental Protection and Regional Development, 283 Laurel Industries Inc., 236, 241 Laxnii Organic hidustries Ltd., 173 Lead - metallic and inorganic compomids, 82 Lead acetate, 82 Lead arsenate, 82 Lead chloride, 82... 

Reactions of solid metals with liquid metals (e.g. dissolution of aluminium in mercury) Dissolution of metal in their fused halides (e.g. lead in lead chloride). 

The predictions of the pH/potential diagram are generally fulfilled, but in very concentrated acid solutions, attack may diminish, owing to the relative insolubility of the relevant salt in the acid. Thus, lead nitrate, although soluble in water, has (owing to common ion effect) only slight solubility in concentrated nitric acid, and the corrosion rate is reduced. Similarly, lead chloride is less soluble in moderately concentrated hydrochloric acid than... 

It should be noted that lead dioxide will discharge if electronically connected to a more base material, when in an unenergised state. The reverse current leakage of a rectifier will allow this to happen to a small extent if the rectifier is faulty, with the consequent formation of lead chloride and corrosion of the anode. 

Consider the process by which lead chloride dissolves in water ... 

To consider a more complicated example, consider the application of expression (2) to the solubility of lead chloride, PbCl2 ... 

A non-thiol precursor, a solid lead chloride-octanoate complex, produces mendi-pite nanobelts after being heated in air for 1 h at 190 °C (Fig. 20.4). A remark-... 

Another way to obtain, under suitable conditions, stable dispersions of sur-factant-stabihzed nanoparticles consists in the direct suspension of some materials in w/o microemulsions. The formation of stable dispersions of rutile (size 80-450 mn) and carbon black (200-500 nm) in AOT// -xylene and of rutile, lead chloride, aluminium, antimony in solutions of calcium soaps in benzene has been reported [219,220],... 

Three types of accidents have been mentioned involving lead chloride (detonation, when it was heated with calcium), carbonate (violent combustion in fluorine) and sulphate (violent reaction, sometimes detonation with potassium). 

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