Barium and compounds

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Agency for Toxic Substances and Disease Registry (ATSDR). 2007. Toxicological profile for barium and compounds (update 2007). Atlanta, GA U.S. Department of Health and Human Services, Public Health Service. 

In general, the chemistry of inorganic lead compounds is similar to that of the alkaline-earth elements. Thus the carbonate, nitrate, and sulfate of lead are isomorphous with the corresponding compounds of calcium, barium, and strontium. In addition, many inorganic lead compounds possess two or more crystalline forms having different properties. For example, the oxides and the sulfide of bivalent lead are frequendy colored as a result of their state of crystallisation. Pure, tetragonal a-PbO is red pure, orthorhombic P PbO is yeUow and crystals of lead sulfide, PbS, have a black, metallic luster. 

In spite of widespread usage of these compounds, the stmctures of only the calcium, barium, and strontium compounds are reasonably weU-estabhshed. The materials are generally made by trituratiag the oxides, or hydroxides, with aqueous hydrogen peroxide and dryiag the soHd products. The commercial products are typically mixtures of the peroxides with varyiag amounts of hydroxides, oxides, carbonates, hydrates, and peroxohydrates. 

Barium can also be deterruined by x-ray fluorescence (XRF) spectroscopy, atomic absorption spectroscopy, and flame emission spectroscopy. Prior separation is not necessary. XRF can be appHed directly to samples of ore or products to yield analysis for barium and contaminants. AH crystalline barium compounds can be analy2ed by x-ray diffraction. 

Calcium [7440-70-2J, Ca, a member of Group 2 (IIA) of the Periodic Table between magnesium and strontium, is classified, together with barium and strontium, as an alkaline-earth metal and is the lightest of the three. Calcium metal does not occur free in nature however, in the form of numerous compounds, it is the fifth most abundant element constituting 3.63% of the earth s cmst. 

Numerous other specialty cements composed of various magnesium, barium, and strontium compounds as siUcates, aluminates, and phosphates, as well as others, are also produced (85). 

Rust inhibitor T0 eliminate rusting in presence of moisture Polar compounds, such as metallic soaps, esters and derivatives of dibasic acids barium and calcium sulphonates... 

A.B. Tsent-Kurnakova R.P. Vasd eva, Synthesis of Calcium, Strontium, and Barium Peroxide Compounds in Hydrogen Peroxide Vapours , IzvAkadNaukSSSR,SerKhim (12), 2738-40 (1967) CA 68, 110875 (1968)... 

D.ll Write the formula for the ionic compound formed from (a) zinc and fluoride ions (b) barium and nitrate ions (c) silver and iodide ions (d) lithium and nitride ions (e) chromium(IIl) and sulfide ions. 

Phase Diagrams, Intermetallic Phases and Compounds 7.3.3.1.5. Barium Systems. 

C08-0074. Consider three possible ionic compounds formed by barium and oxygen Ba O, Ba O, and Ba O . (a) Which would have the greatest lattice energy (b) Which would require the least energy to form the ions (c) Which compound actually exists, and why ... 

One of the most exciting developments in materials science in recent years involves mixed oxides containing rare earth metals. Some of these compounds are superconductors, as described in our Chemistry and Technology Box. Below a certain temperature, a superconductor can carry an immense electrical current without losses from resistance. Before 1986, it was thought that this property was limited to a few metals at temperatures below 25 K. Then it was found that a mixed oxide of lanthanum, barium, and copper showed superconductivity at around 30 K, and since then the temperature threshold for superconductivity has been advanced to 135 K. 

Write formulas for the compounds formed by the reaction of (a) sodium and sulfur, (b) barium and bromine, (c) aluminum and oxygen, (d) lithium and nitrogen, (e) magnesium and nitrogen, (/) aluminum and fluorine, and (g) magnesium and sulfur. 

Why are barium- and iodine-based materials selected for contrast media The production of X-ray images depends on the differences between the X-ray absorbing power of various tissues. This difference in absorbing power is called contrast and is directly dependent on tissue density. To artificially enhance the ability of a soft tissue to absorb X-rays, the density of that tissue must be increased. The absorption by targeted soft tissue of aqueous solutions of barium sulfate and iodized organic compounds provides this added density through the heavy metal barium and the heavy nonmetal iodine. 

The desulfurization process can be carried out either, in a dedicated reactor, or within a simple storage vessel, or during transportation (in pipelines) or intermediate processing vessels. Nutrients addition, pH, and aeration are adjusted as necessary. Multiple stages can be added to the reaction to enhance the sulfur removal process and decrease the reaction time below the probable 300 h required. The produced sulfates are removed by the addition of agents such as alkaline calcium, magnesium, aluminum, barium, and metal compounds such as oxides, hydroxides, and carbonates. 

Sulfate scaling poses a special problem in oil fields of the North Sea (e.g., Todd and Yuan, 1990, 1992 Yuan et al., 1994), where formation fluids are notably rich in barium and strontium. The scale can reduce permeability in the formation, clog the wellbore and production tubing, and cause safety equipment (such as pressure release valves) to malfunction. To try to prevent scale from forming, reservoir engineers use chemical inhibitors such as phosphonate (a family of organic phosphorus compounds) in squeeze treatments, as described in the introduction to this chapter. 

Beryllium and magnesium belong to the 2nd group of the Periodic Table together with calcium, strontium, barium and radium. Characteristic differences, however, may be noticed between the chemistry of Be and Mg and that of the alkaline earth s proper. Be has a unique chemical behaviour with a predominantly covalent character. The heavier elements (Ca, Sr, Ba, Ra) have a predominant ionic behaviour in their compounds. Mg has a chemistry in a way intermediate but closer to that of Be. Analogies between the Mg and Zn chemistries may also be underlined. 

J. J. Zuckerman (Cornell University) Would Dr. Herber and Dr. Sano like to propose the barium tin compound as a standard in Mossbauer spectroscopy—a standard we desperately need at this point. 

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