Lead selenates

A phase diagram and related information of the system Pb0-Se03-H20 at 373.15 K are available in [810IK/GOS]. Only PbSe04(cr) is formed. 

The uncertainty is twice the standard deviation. There is no indication in the data of the formation of PbSe04(aq) at higher selenate concentrations. 

Feroci, Fini, Badiello, and Breccia [97FER/FIN] studied the complex formation between and SeO by classical polarography in 0.15 M NaN03. They found no evidence for an interaction, see Appendix A. The review estimates from an assumed accuracy of the polarographic measurement of 2 mV, the equilibrium constant of the reaction  

Selivanova, Kapustinskii, and Zubova [59SEL/KAP] determined the enthalpy of Reaction (V.61) from the temperature dependence of the solubility product and by a calorimetric measurement of the enthalpy of the reaction  

The review has reconsidered the data and selects from a calculation presented in Appendix A [59SEL/KAP]  

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X 16,000 = 9,467 pounds from lead selenate (round to 9,500 pounds)... 

Reaction with sodium selenate yields lead selenate, PbSe04. Similarly, with sodium selenite or selenious acid, the product is lead selenite, PbSeOs. 

Selenic Acid, HaSe04.—This acid was first prepared by Mitscher-lich in 1827, who suspended lead selenate in water and precipitated the lead by means of hydrogen sulphide. By the oxidation of aqueous solutions of selenious acid with suitable reagents, e.g. chlorine or bromine, selenic acid may also be obtained.6 When chlorine is used, any hydrogen chloride must be removed as soon as it is formed, for selenic acid is reduced by hot hydrogen chloride to selenious acid, with liberation of chlorine the process is best carried out6 by passing a... 

PbSe (c). Fabre1 found <2=40.1 for the reaction of aqueous lead acetate with gaseous hydrogen selenide whence, for PbSe (c), <2/=21.2, For the heat of solution of crystalline lead selenide in saturated bromine water to form lead selenate Fabre1 found 92.1 whence, for PbSe (c),... 

PbSe (s) PbSe04 (s) Lead Selenate 04PbSe (s) PbSe04 (s)... 

The standard Gibbs energy of formation of lead selenate is calculated from the Gibbs energy of Reaction (V.61) and the selected values of AfG° for the ions to be ... 

SEL/BOG] Selivanova, N. M., Boguslavskii, R. Y., Solubility of lead selenate in aqueous solutions of alkali metal selenates, Zh. Fiz. Khim., 29,... 

A 10.00 mL sample of a saturated lead selenate solution is found to contain 0.00136 g of dissolved PbSeO at 25°C. Determine the of lead selenate. 

Pb20(S04) retains this structure up to its melting point of 975 °C. The lanarkite structure is obviously adopted also by lead selenate, chromate and molybdate. Nothing is known of corresponding Sn salts. Isoelectronic Bi20(Si04) and... 

Lead(II) sulphate is precipitated from lead(II) solutions by sulphate ions, and is one of the popular gravimetric precipitates for lead. Its increased solubility in concentrated sulphuric acid suggests formation of sulphato or bisulphato complexes of lead(II). Lead selenate is precipitated similarly from Pb++ and SeO mixing. 

The ease with which the dipolarophile interacts with vinylacetylenes depends mainly on a spatial factor. The study of the reactions of alkylthiobuten-3-ynones-l and their selenic and telluric analogs with DPNT shows that, in this case, nitrilimine also acts as a nucleophilic agent with a nucleophilic center on the carbon atom of the 1,3-dipole and always adds to the terminal carbon of the enyne system to form l,3-diphenyl-5-/ -2-pyrazolenines. The oxidation of the latter with chloranil leads to alkynylpyrazoles (65ZOR51). 

Selen-. selenium, selenlc, selenide of, seleno-.. ammonium, n. ammonium selenide. -dthyl, n. ethyl selenide. -blei, n. lead selenide. 

Selenium was discovered in 1817 by J. J. Berzelius (1779-1848) and J. G. Gahn (1745-1818) in the sediment taken from the lead chamber of a sulfuric acid plant in Gripsholm, Sweden. Its name was derived from the Greek word aekr]vr] (selene), for moon, because of its chemical similarity to tellurium-earth. 

Aqueous electrolytes proposed in the literature for cathodic electrodeposition of lead selenide are generally composed of dissolved selenous anhydride and a lead salt, such as nitrate or acetate. Polycrystalline PbSe films have been prepared by conventional electrosynthesis from ordinary acidic solutions of this kind on polycrystalline Pt, Au, Ti, and Sn02/glass electrodes. The main problem with these applications was the PbSe dendritic growth. Better controlled deposition has been achieved by using EDTA in order to prevent PbSeOs precipitation, and also acetic acid to prevent lead salt hydrolysis. 

The formation of silaneselone 57 was evidenced by the trapping reaction with mesitonitrile oxide leading to the corresponding cycloadduct 58 and was also supported by the observation of a remarkably downfield 29Si chemical shift (8Si = 174) indicative of the Si=Se double bond of 57. Although this direct selenation of silylene 55 with an equimolar amount of selenium was not reproducible, the use of excess amount of elemental selenium resulted in the formation of a new cyclic diselenide, diselenasilirane 59, as a stable compound (8Si = -44 and... 

A variation of the CD process for PbSe involved deposition of a basic lead carbonate followed by selenization of this film with selenosulphate [64]. White films of what was identified by XRD as 6PbC03-3Pb(0H)2-Pb0 (denoted here as Pb—OH—C) were slowly formed over a few days from selenosulphate-free solutions that contained a colloidal phase and that were open to air (they did not form in closed, degassed solutions). CO2 was necessary for film formation—other than sparse deposits, no film formation occurred of hydrated lead oxide under any conditions attempted in this study. Treatment of these films with selenosulphate solution resulted in complete conversion to PbSe at room temperature after 6 min. The selenization process of this film was followed by XRD, and it was seen to proceed by a breakdown of the large Pb—OH—C crystals to an essentially amorphous phase of PbSe with crystallization of this phase to give finally large (ca. 200 nm) PbSe crystals covered with smaller (15-20 nm) ones as well as some amorphous material. 

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