Barium sulfate, decomposition

Holloway JR, Blank JG (1994) Application of experimental results to C-O-H species in natural melts. In MR Carroll, JR Holloway (eds.) Volatiles in magmas. Rev Miner 30 187-230 Holser WT (1977) Catastrophic chemical events in the history of the ocean. Nature 267 403 08 Holser WT, Kaplan IR (1966) Isotope geochemistry of sedimentary sulfates. Chem Geol 1 93-135 Holt BD, Engelkemeier AG (1970) Thermal decomposition of barium sulfate to sulfur dioxide for mass spectrometric analysis. Anal Chem 42 1451-1453 Hoppe P, Zinner E (2000) Presolar dust grains from meteorites and their stellar sources. J Geophys Res Space Phys 105 10371-10385... 

Barium hydroxide decomposes to barium oxide when heated to 800°C. Reaction with carbon dioxide gives barium carbonate. Its aqueous solution, being highly alkahne, undergoes neutrahzation reactions with acids. Thus, it forms barium sulfate and barium phosphate with sulfuric and phosphoric acids, respectively. Reaction with hydrogen sulfide produces barium sulfide. Precipitation of many insoluble, or less soluble barium salts, may result from double decomposition reaction when Ba(OH)2 aqueous solution is mixed with many solutions of other metal salts. 

In an atmosphere of nitric oxide, thermal decomposition produces barium nitrite, Ba(N02)2. Reactions with soluble metal sulfates or sulfuric acid yield barium sulfate. Many insoluble barium salts, such as the carbonate, oxalate and phosphate of the metal, are precipitated by similar double decomposition reactions. Ba(N03)2 is an oxidizer and reacts vigorously with common reducing agents. The solid powder, when mixed with many other metals such as aluminum or zinc in their finely divided form, or combined with alloys such as... 

Barium sulfate is one of the most insoluble salts of barium. It does not undergo double decomposition reactions in aqueous phase. It dissolves in concentrated H2SO4 to form an acid sulfate which breaks down to BaS04 upon dilution. 

Fig. 27. The relationship between particle size and decomposition rate of barium sulfate on the NSR catalyst.

Nitro substituents and heterocyclic nitrogen influence not only the yield of fluorodediazoniation but also the rate of decomposition which, in these cases, is too high to perform the reaction on a multigram scale. Some explosions have been reported. Thus, the decomposition of nitro-substituted or heterocyclic diazonium tetrafluoroborates is usually controlled by three-to fivefold dilution of these substrates in inert solids, such as acid-washed sand,113 218 Kiesel-guhr,3 sodium carbonate,3 barium sulfate,217 sodium fluoride,216 or sodium tetrafluoroborate.3 This modified technique has been generalized to the decomposition of all kinds of diazonium tetrafluoroborates under safe conditions, even on rather large scales. 

Barium sulfate (BaS04, melting point 1580°C with decomposition) occurs as colorless rhombic crystals. It is soluble in concentrated sulfuric acid, forming an acid sulfate dilution with water reprecipitates barium sulfate. Precipitated barium sulfate, known as blancfixe, is prepared from the reaction of aqueous solutions of barium sulfide (BaS) and sodium sulfate (Na2S04). 

Barium Sulfate—BaSOa—232,8—occurs in nature as heavy spai and is formed as an amorphous, white powder, insoluble in acids, by double decomposition between a Ba salt and a sulfite in solution. It is insoluble in HaO and in acids. It is used as a pig--inent, permanent white. 

The decomposition of other oxysalts, such as nitrates and sulfates, follows the same rules. Barium sulfate can be heated to bright redness without decomposition, as the analytical chemist knows calcium sulfate loses some SOj... 

Aqueous solutions of chloric and bromic acids are formed by disproportionation of CI2 or Br2 in hot alkaline solution [Eq. (15) and (16)] or by treating the appropriate barium halate salt with sulfuric acid and removing the precipitated barium sulfate [similar to Eq. (41)]. Concentration of these solutions leads to decomposition of the acid. 

Barium sulfate, as such or in the form of lithopones (BaS04 + ZnS, or + CdS) is used as pigment. It also constitues a weighting material in the manufacture of special papers. It can be easily detected in pigments or the ash of papers because it is completely converted into barium chloride by ignition with ammonium chloride. The conversion is due to the production of hydrogen chloride in the thermal decomposition of ammonium chloride and the gas is formed at about 400 C, in other words at a temper-... 

Thermal Decomposition. Cesium a2ide [22750-57-8] CsN, which is prepared by reacting aqueous solutions of cesium sulfate and barium a2ide, melts at 326°C and decomposes at 390°C to cesium metal (32) ... 

The removal of inorganic salts from reaction mixtures afforded by polymeric materials may be simply and effectively accomplished by dialysis,166 178 after decomposition of remaining periodate with ethylene glycol130 131 or butylene glycol. 161 170 Alternatively, the iodate and periodate ions may be removed as such, or after reduction to free iodine. The iodate and periodate ions have been effectively precipitated by means of sodium carbonate plus manganous sulfate,6 or by lead dithionate,191 barium chloride,24 192 193 strontium hydroxide194 202 or barium hydroxide,203 204 lead... 

Barium acetate converts to barium carbonate when heated in air at elevated temperatures. Reaction with sulfuric acid gives harium sulfate with hydrochloric acid and nitric acid, the chloride and nitrate salts are obtained after evaporation of the solutions. It undergoes double decomposition reactions with salts of several metals. For example, it forms ferrous acetate when treated with ferrous sulfate solution and mercurous acetate when mixed with mercurous nitrate solution acidified with nitric acid. It reacts with oxahc acid forming barium oxalate. 

Pass carbon dioxide through the filtrate until all excess of barium hydroxide has been precipitated as carbonate filter and evaporate to crystallization. Other dithio-nates can be prepared from the barium salt by double decomposition with sulfates of other metals. 

AZIDA SODICA (Spanish) (26628-22-8) Reacts with hot water. Explosive decomposition in elevated temperatures above 525°F/274°C. Forms ultra-sensitive explosive compounds with heavy metals copper, copper alloys, lead, silver, mercury, carbon disulfide, trifluoroacryloyl fluoride. Violent reaction with acids, forming explosive hydrogen azide. Violent reaction with bromine, barium carbonate, chromyl chloride, dimethyl sulfate, dibromomalononitrile. Incompatible with caustics, cyanuric chloride, metal oxides, metal sulfides, methyl azide, phosgene. 

---