Oxygen barium

Brin An obsolete process for making oxygen. Barium monoxide was roasted in air to produce barium peroxide, which was roasted at a higher temperature to produce oxygen ... 

Soda-Lime. There is an exothermic reaction between granular soda-lime and hydrogen sulfide that results in a violent explosion in the presence of oxygen. Barium hydroxide and sodium or potassium hydroxides behave similarly.6... 

Group 2 All burn to form ionic oxides of formula MO, except that in excess oxygen barium forms a peroxide (Ba02). 

Bomb Method the sample is burned in a bomb under oxygen pressures of 30 bar. The sulfur contained in the wash water is analyzed via gravimetry as barium sulfate. 

Barium is a metallic element, soft, and when pure is silvery white like lead it belongs to the alkaline earth group, resembling calcium chemically. The metal oxidizes very easily and should be kept under petroleum or other suitable oxygen-free liquids to exclude air. It is decomposed by water or alcohol. 

Cm ORINE OXYGEN ACIDS AND SALTS - DICm ORINE MONOXIDE, HYPOCm OROUS ACID, AND HYPOCm ORITES] (Vol 5) Barium hypophosphite [14871-79-5]... 

Oxygen Octahedra. An important group of ferroelectrics is that known as the perovskites. The perfect perovskite stmcture is a simple cubic one as shown in Figure 2, having the general formula ABO, where A is a monovalent or divalent metal such as Na, K, Rb, Ca, Sr, Ba, or Pb, and B is a tetra- or pentavalent cation such as Ti, Sn, Zr, Nb, Ta, or W. The first perovskite ferroelectric to be discovered was barium titanate [12047-27-7] and it is the most thoroughly investigated ferroelectric material (10). 

Laser isotope separation techniques have been demonstrated for many elements, including hydrogen, boron, carbon, nitrogen, oxygen, sHicon, sulfur, chlorine, titanium, selenium, bromine, molybdenum, barium, osmium, mercury, and some of the rare-earth elements. The most significant separation involves uranium, separating uranium-235 [15117-96-1], from uranium-238 [7440-61-1], (see Uranium and uranium compounds). The... 

Peroxides, superoxides, and chlorates are oxidising compounds and should not contact organic materials, eg, oil, greases, etc. This is especially tme while oxygen is being produced. Caustic residues that may remain after use of peroxides and superoxides require disposal appropriate to alkaH metal hydroxides. Spent candles containing barium may require special disposal considerations. 

The commercial product is a dull yeUow powder containing about 90% Ba02 and about 8.5% active oxygen the remainder is mainly barium carbonate and barium hydroxide. The principal use is in pyrotechnics, but there are also small uses in the curing of polysulftde mbbers and in the production of certain titanium—aluminum alloys. 

Barium titanate [12047-27-7] has five crystaUine modifications. Of these, the tetragonal form is the most important. The stmcture is based on corner-linked oxygen octahedra, within which are located the Ti" " ions. These can be moved from their central positions either spontaneously or in an apphed electric field. Each TiO octahedron may then be regarded as an electric dipole. If dipoles within a local region, ie, a domain, are oriented parallel to one another and the orientation of all the dipoles within a domain can be changed by the appHcation of an electric field, the material is said to be ferroelectric. At ca 130°C, the Curie temperature, the barium titanate stmcture changes to cubic. The dipoles now behave independentiy, and the material is paraelectric (see Ferroelectrics). 

Finely divided barium is susceptible to rapid, violent combination with atmospheric oxygen. Therefore, in powdered form it must be considered pyrophoric and very dangerous to handle in the presence of air or other oxidising gases. Barium powder must be stored under dry argon or helium to avoid the possibihty of violent explosions. Massive pieces of barium, however, oxidize relatively slowly and present no explosion hazard if kept dry. 

Barium oxide, which can react directly with oxygen to give the peroxide (33), is soluble in methanol and ethanol forming the alkoxides (see... 

The thermodynamics of the 123 compound have been extensively studied and writing dre formula as (YBa2Cu3)Oj. it has been shown that at 1000 K the value of z changes from 6 to 6.6 in dre oxygen pressure range 10 " to one atmosphere of oxygen. Above this temperature, the 123 compound decomposes to 211 plus barium cuprate and cuprous oxide according to the reaction... 

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