Lead monoxide, 5.32

Red lead is a brilliant red powder obtained by heating lead monoxide in air to about 800 K. This reaction is reversible, for if heated, red lead evolves oxygen at temperatures above 850 K. 

Tetravalent lead is obtained when the metal is subjected to strong oxidizing action, such as in the electrolytic oxidation of lead anodes to lead dioxide, Pb02 when bivalent lead compounds are subjected to powerful oxidizing conditions, as in the calcination of lead monoxide to lead tetroxide, Pb O or by wet oxidation of bivalent lead ions to lead dioxide by chlorine water. The inorganic compounds of tetravalent lead are relatively unstable eg, in the presence of water they hydrolyze to give lead dioxide. 

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. 

Lead Monoxide. Lead monoxide (litharge), PbO, occurs as a reddish alpha form, which is stable up to 489°C where it transforms to a yellow beta form (massicot). The latter is stable at high temperatures. The solubihty of a-PbO ia water is 0.0504 g/L at 25°C the solubihty of the p-PbO is 0.1065 g/L at 25°C (40). Lead monoxide is amphoteric and dissolves ia both acids and alkahes. In alkahes, it forms the plumbite ion PbO - The monoxide is produced commercially by the reaction of molten lead with air or oxygen ia a furnace. Black or gray oxide is manufactured by the Barton process, by the oxidation of atomized molten lead ia air, as well as by the ball mill process, ia which metallic lead balls of high purity are tumbled ia the mill to form partially oxidized lead particles. 

Lead Tetroxide. Lead tetroxide (red lead minium lead orthoplumbite), Pb O, is a brilliant orange-red pigment which accounted for U.S. shipments of 17,780 t ia 1977, mainly to the ceramics and storage battery iadustries (40). U.S. shipments ia 1993 amounted to approximately 12,000 t. The decrease ia usage siace 1973 (19,000 t) is attributable to discontinued use ia the paint and coatings (qv) iadustry, and alterations ia mbber and ceramics (qv) markets. It is iasoluble ia water and alcohol, and dissolves ia acetic acid or hot hydrochloric acid. Red lead is manufactured by heating lead monoxide ia a reverberatory furnace ia the preseace of air at 450—500°C uatil the desired oxidative composition is obtaiaed. 

Lead nitrate [10099-74-8] Pb(N02)2, mol wt 331.23, sp gr 4.53, forms cubic or monoclinic colorless crystals. Above 205°C, oxygen and nitrogen dioxide are driven off, and basic lead nitrates are formed. Above 470°C, lead nitrate is decomposed to lead monoxide and Pb O. Lead nitrate is highly soluble in water (56.5 g/100 mL at 20°C 127 g/100 mL at 100°C), soluble in alkalies and ammonia, and fairly soluble in alcohol (8.77 g/100 mL of 43% aqueous ethanol at 22°C). Lead nitrate is readily obtained by dissolving metallic lead, lead monoxide, or lead carbonate in dilute nitric acid. Excess acid prevents the formation of basic nitrates, and the desired lead nitrate can be crystallized by evaporation. 

Certain perovskites with Pb on the A site are particularly important and show pronounced piezoelectric characteristics (PbTiO, PZT, PLZT). Different responses are found in BaTiO and PZT to the addition of donor dopants such as La ". In PZT, lead monoxide [1317-36-8] PbO, lost by volatilization during sintering, can be replaced in the crystal by La202, where the excess positive charge of the La " is balanced by lead vacancies, leading to... 

Lead monoxide [1317-36-8] M 223.2, m 886°. Higher oxides were removed by heating under vacuum at 550° with subsequent cooling under vacuum. [Ray and OggJ Am Chem Soc 78 5994 1956.]... 

About 5 minutes later, the liquid contents of the beaker are poured cautiously into a 2-1. glass beaker, and this is tipped and rotated slowly so as to spread the congealing mass in a thin film on the beaker walls. When the material in the beakers has cooled, a total of 11. of water is poured into the beakers and the water is stirred well for at least 1 hour (Note 5). The cold suspension is filtered with suction to separate 200-210 g. of an insoluble mixture of lead monoxide and red lead, which is washed on the filter with six 50-ml. portions of water. 

Chemical Designations - Synonyms Lead monoxide Lead oxide, yellow Lead protoxide Massicot Plumbous oxide Chemical Formula PbO. 

Sulphates, silicates, carbonates, colloids and certain organic compounds act as inhibitors if evenly distributed, and sodium silicate has been used as such in certain media. Nitrates tend to promote corrosion, especially in acid soil waters, due to cathodic de-polarisation and to the formation of soluble nitrates. Alkaline soils can cause serious corrosion with the formation of alkali plumbites which decompose to give (red) lead monoxide. Organic acids and carbon dioxide from rotting vegetable matter or manure also have a strong corrosive action. This is probably the explanation of phenol corrosion , which is not caused by phenol, but thought to be caused by decomposition of jute or hessian in applied protective layers. ... 

Synonym(s) Chromic acid, lead and molybdenum salt lead chromate, sulphate and molybdate molybdenum-lead chromate molybdenum orange Lead dinitrate nitric acid lead(2+) salt lead (II) nitrate plumbous nitrate Lead(2+) oxide lead monoxide litharge massicot Lead(2+) phosphate Phosphoric acid lead(2+) salt ... 

Lead monoxide, PbO, formerly used as an inorganic accelerator but now mainly used as a vulcanising agent in some polychloroprene... 

Lead monoxide or litharge is mainly used as an accelerator activator, and acid acceptor, and is especially useful in water resistant compounding. Litharge can also be used in long slow cures for such articles as ship s fenders, bridge bearings, etc., where it enables the inside of the product to fully cure before the outside becomes overcured with the possibility of degradation or reversion of the outer layer of the product. 

Pascal, P., Ed., Nouveau Traite de Chimie Minerale, Vol. 13, Masson et Cie., Paris, 1960, 528. Barton A process for making black lead monoxide by atomizing molten lead in air. BASF/CAN See CAN. 

Bischof An obsolete process for making white lead (basic lead carbonate), invented by G. Bischof around 1900. Lead monoxide was reduced by the carbon monoxide in water-gas to form black lead suboxide, oxidized in damp air to lead hydroxide, slurried in dilute acetic acid, and carbonated with carbon dioxide. Piloted in Willsden, London, and commercialized by L. Mond in the Brimsdown White Lead Company. A sample of Bischof s white lead was used by Holman Hunt in his painting Light of the World, now in St. Paul s Cathedral, London. 

Carter Also known as H.T.S. Carter. A proces for making basic lead carbonate pigment (white lead). Lead monoxide, in a slowly revolving drum, is moistened and sprayed with acetic acid. Carbon dioxide is then introduced. Carbonation is subsequently completed in a separate vessel. See also Dutch, Thompson-Stewart. 

Cupellation An ancient metallurgical operation, still in use, for removing lead and other base metals from silver by blowing air over the surface of the molten metal. The lead oxidizes to lead monoxide (litharge), which floats on the molten silver and is separated off. The molten litharge dissolves the other base metal oxides present. A cupel is the shallow refractory dish in which the operation is conducted. 

Thenard A process for making white lead pigment (basic lead carbonate) by boiling litharge (lead monoxide) with lead acetate solution and passing carbon dioxide gas into the suspension. 

Thompson-Stewart A process for making basic lead carbonate ( white lead, 2PbC03Pb(0H)2), by reacting lead monoxide ( litharge ) with acetic acid and then with carbon dioxide. Basic lead acetate is an intermediate. See also Dutch, Carter. 

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