Bismuth selenites

Andreeva and Karapet yants [65AND/KAR], [66AND/KAR] performed calorimetric measurements from which the standard enthalpies of formation of Bi2(Se03)3(cr) and (Bi0)2Se03(cr) were found. Their data have been re-evaluated with new auxiliary data in Appendix A. The result is //° (Bi2(Se03)3, cr, 298.15 K) = 

However, according to Oppermann et al. [990PP/G0B] the decomposition of (BiO)2Se03(cr) to Bi203(cr) and Se02(g) comprises additional steps. Therefore no thermochemical data have been calculated by the review from these relationships. 

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Andreeva and Karapet yants prepared crystalline bismuth selenite and measured in a calorimeter its enthalpy of dissolution in HN03(aq, 1 9) denoted sin. The enthalpies of dissolution of bismuth nitrate and selenious acid in the same solvent were also determined. The numerical values used in the thermochemical cycle in the paper indicate that the compound denoted there by Bi(N03)3(cr) is in fact Bi(N03)3-5H20 (cr). The data were evaluated on this assumption in Table A-47. The partial standard molar enthalpies of formation of H2O and HNO3 were estimated from [82WAG/EVA]. 

MAR/SAP] Markovskii, L. Y., Sapozhnikov, Y. P., Boev, E. I., Bismuth selenites, Zh. Neorg. Khim., 9, (1964), 856-866, in Russian, English translation in [64MAR/SAP2]. Cited on page 203. 

AND/KAR] Andreeva, L. L., Karapet yants, M. K., Heats of formation of bismuth selenite and tellurite, Zh. Fiz. Khim., 40, (1966), 470-473, in Russian, English translation in [66AND/KAR2]. Cited on pages 202, 484. 

BAK/PAS] Bakeeva, S. S., Pashinkin, A. S., Bakeev, M. 1., Dissociation pressure of bismuth selenite, Tr. Khim.-Metall. Inst. Akad. Nauk Kaz. SSR, 19, (1972), 130-135, in Russian. Cited on page 203. 

USE Photographic fixing agent and to remove stains from negatives manuf resins vulcanization accelerator a reagent for bismuth, selenite ions. 

The properties of anodic layers of HgS formed on mercury in sulfide solutions have been investigated in comparison with anodic sulfide layers of cadmium and bismuth. Also, the electrochemistry of mercury electrodes in aqueous selenite solutions has been studied (see Sect. 3.2.1). The problem with the presence of several cathodic stripping peaks for HgSe in acidic Se(IV) solutions has been addressed using various voltammetric techniques at a hanging-mercury-drop electrode [119]. 

Alkaline-Earth Sulfides and Sulfoselenides. Activated alkaline-earth sulfides have been known for a long time their luminesence is very varied. Emission bands between the ultraviolet and near infrared can be obtained by varying the activation. They are produced by precipitation of sulfates or selenites from purified solutions, followed by reduction with Ar-H2. The addition of activators, for example, copper nitrate, manganese sulfate, or bismuth nitrate, is followed by firing for 1 - 2 h. Alkaline-earth halides or alkali-metal sulfates are sometimes added as fluxes. 

Black precipitate of bismuth metal Violet coloration with stannous salts the following interfere strong reducing agents (hydrogen sulfide, dithionites, sulfites, and selenites) also, U, V, Te, Hg, Bi, Au, Pd, Se, Sb... 

Thiourea test, CS(NH2)2. Solid or dissolved thiourea precipitates selenium as a red powder from cold dilute solutions of selenites. Tellurium and bismuth give yellow precipitates, whilst large amounts of nitrite and of copper interfere. 

Occurrence, — Selenium must be considered a rare element, although it is found widely distributed in nature. The distinctive selenium minerals are rare, and they are usually selenides, of such metals as lead, mercury, copper, bismuth, and silver. The element is also found in the free state associated with sulfur and as a selenite. The most common occurrence of selenium is in ores in which the element has partially displaced sulfur. Generally the selenium is present in very small proportions, but on account of the fact that enormous quantities of sulfide ores are used, this represents a considerable amount of selenium. It occurs also in small amounts in meteoric iron, in volcanic lavas, and in certain deposits of coal. Traces of selenium have been detected in rain and snow. Even though present in mineral ores in mere traces, it is readily concentrated either in the flue dusts or in the anode mud of the electrolytic refineries. Considerable quantities are known to exist in Hawaii, Japan,... 

Cray, hexagonal, microscopic needles, mp 880. d<5 8.216. Two forms exist transition temp at 133. Forms metallic silver and selenium oxide when heated in oxygen transformed by chlorine into silver and selenium chlorides oxidized to silver selenite by fuming nitric acid. So] in mol ten silver or bismuth without chemical change. Practically insol in water. 

Paul and coworkers (1989) have investigated the antidotal actions of several compounds on the acute toxicity of selenium in rats. Male Wistar rats were injected sodium [ Sejselenite subcutaneously in this study. Intraperitoneal administration of diethyldithiocarbamate or treatment with citrate salt of bismuth, antimony, or germanium, administered subcutaneously, reduced selenium-induced loss of body weight in the animals. Germanium citrate and bis(carboxyethyl)germanium sesquiox-ide promoted increases in the 24-hour urinary excretion of selenium when administered 15 minutes after sodium selenite. 

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