Hexafluoride chemical properties

Most chemical properties of technetium are similar to those of rhenium. The metal exhibits several oxidation states, the most stable being the hep-tavalent, Tc +. The metal forms two oxides the black dioxide Tc02 and the heptoxide TC2O7. At ambient temperature in the presence of moisture, a thin layer of dioxide, Tc02, covers the metal surface. The metal burns in fluorine to form two fluorides, the penta- and hexafluorides, TcFs and TcFe. Binary compounds also are obtained with other nonmetaUic elements. It combines with sulfur and carbon at high temperatures forming technetium disulfide and carbide, TcS2 and TcC, respectively. 

B) R. DeWitt, Uranium Hexafluoride A Survey of the Physico-Chemical Properties , GAT-280, Goodyear Atomic Corp, Portsmouth, Contract AT<33-2>1 (1960) C) L.S. Allen, A Parametric Survey of Criticality-Limited Fast Reactors Employing Uranium Fluoride Fuels , TR32-198, Jet Propulsion Lab, Contract NAS-7-100 (1962) D) C.A. Geffen et al, Assessment of the Risk of Transporting Uranium Hexafluoride by Truck and Train , Battelle, Richland, Contract EY-76-C-06-1830 (1978)... 

Element 106. The chemical properties of element 106 (eka-tungsten) are predicted to be similar to those of tungsten, molybdenum and to some extent chromium, offering an even richer chemistry of complex ions than these elements. The hexafluoride should be quite volatile and the hexachloride, pentachloride and oxychloride should be moderately volatile. Penneman and Mann predict a -)-4 oxidation state in aqueous solution. Jprgensen s selection of k is for the hydrated cation and is not intended to account for the effects of complex ion formation. However, since tungsten is stabilized in the oxidation state of -t-6 by the tungstate ion, an analogous situation may be expected for element 106. 

The discovery of dioxygenyl hexafluoroplatinate(v), revealed the remarkable oxidizing properties of platinum hexafluoride. The crystal structure and m netic, spectroscopic , and chemical properties of 02PtFe all point to the ionic formulation OJ [PtFel". 

D3. DeWitt, R. Uranium Hexafluoride A Sumrrtary of the Physico-Chemical Properties, Report GAT-280, Aug. 12, 1960. 

CHEMICAL PROPERTIES noncombustible liquid or nonflammable gas stable to water in the presence of acid or base disproportionates at 1 °C to sulfur tetrafluoride and sulfur hexafluoride no reactivities or incompatibilities reported. 

CHEMICAL PROPERTIES stable under ordinary conditions of use and storage hydrolyzes slowly in water to telluric acid (H606Te) more quickly hydrolyzed by aqueous potassium hydroxide when pure, does not attack glass corrosive to mercury not as chemically inert as sulfur hexafluoride (SF(,) and selenium hexafluoride (SeFs) because the maximum covalence of tellurium is greater than six FP (NA) LFLZUFL(NA) AT(NA) HC(NA) HF(-1318.0 kJ/mol gas at 25 C) Tc (83 C, 181.4 ). 

Prepare a tabulated report, using tabulated format, on the physical and chemical properties of the raw materials, intermediate products, by-products, and principal chemicals which will be encountered in the manufacture of (a) maleic anhydric hydrazide (fe) ethylene (r) uranium hexafluoride (solvent extraction (/) denatured alcohol from potatoes or any selected industrial chemical product. 

Very little attention has been paid to theoretical predictions of the chemical properties of Mt through element 120 since the 1986 summary of Seaborg and Keller. Based on the positions of Mt and element 112 in the periodic table, they should be noble metals like Pt and Au, and volatile hexafluorides and octafluorides might be produced and used in chemical separation procedures. Early relativistic molecular calculations (Waber and Averill, 1974 Rosen, 1998) suggested that 110F6 should be similar to PtF6. 

Chemical identification is a desirable method for detection of a new element Chemical identification of the elements immediately beyond hahnium (element 105) should be possible, but rapid chemical reactions will be required. Chemical properties can be predicted with the help of the periodic table shown in Fig. 24.1, which indicates that elements 106,107, 108, etc., should be chemical homologs, respectively, of tungsten (W), rhenium (Re), osmium (Os), etc. The utilization of volatility properties perhaps offers the best possibility for very rapid chemical identification. The hexafluoride and hexacarbonyl of element 106 (eka-tungsten) should be quite volatile and the hexachloride, pentachloride, and oxychlorides... 

Few detailed predictions of the chemical properties of elements 109 (eka-iridium) and 110 (eka-platinum) have been made as yet. Their positions in the periodic table indicate that they should be noble metals. If the upper oxidation states are stable, volatile hexafluorides and octafluorides might be useful for chemical separation purposes. The predictions of the most stable oxidation states of elements 109 and 110 deviate widely. Penneman and Mann [17] give an oxidation state of i for 109 and 0 for 110. Cunningham preferred vi for both 109 and 110 [18]. 

The construction of new equipment with higher capacity and improved performance has been made possible by the excellent electrical, thermal and chemical properties of SFg. Changing from conventional dielectrics to sulfur hexafluoride, which is a nonflammable chemically inactive and nontoxic gas with high density, results in considerable space and weight savings. Improvements in the operational safety of converted equipment can also be achieved [41, 42]. 

A practical application of Graham s law arose during World War II, when scientists were studying the fission of uranium atoms as a source of energy. It became necessary to separate which is fissionable, from the more abundant isotope of uranium, which is not fissionable. Because the two isotopes have almost identical chemical properties, chemical separation was not feasible. Instead, an effusion process was worked out using uranium hexafluoride, UFs. This compound is a gas at room temperature and low pressures. Preliminary experiments indicated that could indeed be separated... 

Molybdenum hexafluoride [7783-77-9] MoF, is a volatile liquid at room temperature. It is very moisture sensitive, hydrolysing immediately upon contact with water to produce HF and molybdenum oxyfluorides. MoF should therefore be handled in a closed system or in a vacuum line located in a chemical hood. The crystals possess a body-centered cubic stmcture that changes to orthorhombic below —96° C (1,2). The known physical properties are Hsted in Table 1. 

Sulfur hexafluoride [2551-62-4] 6 molecular weight 146.07, is a colorless, odorless, tasteless gas. It is not flammable and not particularly reactive. Its high chemical stabiUty and excellent electrical characteristics have led to widespread use in various kinds of electrical and electronic equipment such as circuit breakers, capacitors, transformers, microwave components, etc (see Electronic materials). Other properties of the gas have led to limited usage in a variety of unique appHcations ranging from medical appHcations to space research. 

Chemica.1 Properties. With few exceptions, SF is chemically inert at ambient temperature and atmospheric pressure. Thermodynamically SF is unstable and should react with many materials, including water, but these reactions are kineticaHy impeded by the fluorine shielding the sulfur. Sulfur hexafluoride does not react with alkah hydroxides, ammonia, or strong acids. 

T. J. Brice, R. 1. Coon, and W. A. Severson, "Properties of Some Fluorocarbon Derivatives of Sulfur Hexafluoride," paper presented at American Chemical Society, Minneapolis, Minn., 1955. 

The first use of supercritical fluid extraction (SFE) as an extraction technique was reported by Zosel [379]. Since then there have been many reports on the use of SFE to extract PCBs, phenols, PAHs, and other organic compounds from particulate matter, soils and sediments [362, 363, 380-389]. The attraction of SFE as an extraction technique is directly related to the unique properties of the supercritical fluid [390]. Supercritical fluids, which have been used, have low viscosities, high diffusion coefficients, and low flammabilities, which are all clearly superior to the organic solvents normally used. Carbon dioxide (C02, [362,363]) is the most common supercritical fluid used for SFE, since it is inexpensive and has a low critical temperature (31.3 °C) and pressure (72.2 bar). Other less commonly used fluids include nitrous oxide (N20), ammonia, fluoro-form, methane, pentane, methanol, ethanol, sulfur hexafluoride (SF6), and dichlorofluoromethane [362, 363, 391]. Most of these fluids are clearly less attractive as solvents in terms of toxicity or as environmentally benign chemicals. Commercial SFE systems are available, but some workers have also made inexpensive modular systems [390]. 

Chemical and physical properties of the hexafluorides recently have been reviewed by Weinstock (321), who also accounted for the structures of these volatile compounds in the solid state. The vibrational properties of hexafluoride molecules have been summarized by Weinstock and Gooiman (325). 

Composite coatings of tungsten and rhenium are produced by the simultaneous chemical vapor deposition from their hexafluorides [52,53], and the addition of rhenium improves the ductility and high-temperature properties of the deposit. 

Sulfur hexafluoride is unique in its stability and chemical inertness it is a colourless, odourless, tasteless, unreactive, non-flammable, non-toxic, insoluble gas prepared by burning sulfur in an atmosphere of fluorine. Because of its extraordinary stability and excellent dielectric properties it is extensively used as an insulating gas for high-voltage generators and switch gear at a pressure of 2-3 bars it withstands... 

Concurrent with the injection of iron is the injection of the inert chemical tracer sulfur hexafluoride (SFg). By presaturating a tank of sea water with SFg and employing an expandable displacement bladder, a constant molar injection ratio of Fe SFg can be achieved (Figure 6). In this way, both conservative and nonconservative removal of iron can be quantified. Sulfur hexafluoride traces the physical properties of the enriched patch the relatively rapid shipboard detection of SFg can be used to track and... 

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