Carbonates alkali hydrogen

Molten carbonate Alkali- Hydrogen Atmospheric 650°C (1200T) 40%-55% 177, 179, 180... 

Thiazole disulfides are reported to yield quantitatively A-4-thiazoline-2-thiones under treatment with zinc powder in acetic acid (326). The disulfide bond can be broken on heating at 100 to 260°C and (or) by alkali. This property has been used for photographic emulsions (327). The disulfide (136) (R = 4-(D-arabmo-tetrahydroxybutyD can be cleaved readily by aqueous sodium hydroxyde. carbonate, or hydrogen carbonate (149) to give 135 a by-product, 4-(D-arabino-ietrahydroxybutyl) thiazole... 

The elements of primary importance in this context are oxygen, nitrogen, carbon and hydrogen. In the technology of the liquid alkali metals they play a predominant rdle. Their origin is associated with leakages in the circuit, impurities remaining after construction or residual impurities in the liquid metal. It is convenient to discuss these four elements separately. 

With or without acids, alkalis, salts, with exception of aimnonium and sulfite With or without acids, alkalis, salts, in presence of sulfites (sulfurous acid, Na or K sulfite and bisulfite) no ammonium compounds used With or without acids, alkalis, salts, in presence of ammonium compounds (hydroxide, carbonate, ammonium hydrogen carbonate, phosphate) no sulfite used With or without acids, alkalis, salts, in presence of ammonium compounds and sulfite... 

Binary Selenides. Most binary selenides are formed by heating selenium in the presence of the element, reduction of selenites or selenates with carbon or hydrogen, and double decomposition of heavy-metal salts in aqueous solution or suspension with a soluble selenide salt, eg, Na2Se or (NH Se [66455-76-3]. Atmospheric oxygen oxidizes the selenides more rapidly than the corresponding sulfides and more slowly than the tellurides. Selenides of the alkali, alkaline-earth metals, and lanthanum elements are water soluble and readily hydrolyzed. Heavy-metal selenides are insoluble in water. Polyselenides form when selenium reacts with alkali metals dissolved in liquid ammonia. Metal (M) hydrogen selenides of the M HSe type are known. Some heavy-metal selenides show important and useful electric, photoelectric, photo-optical, and semiconductor properties. Ferroselenium and nickel selenide are made by sintering a mixture of selenium and metal powder. 

Pyrolysis, Benzene undergoes thermal dehydrocondensation at high temperatures to produce small amounts of biphenyls and terphenyls (see Biphenyl AND terphenyls). Before the 1970s most commercial biphenyl was produced from benzene pyrolysis. In a typical procedure benzene vapors are passed through a reactor, usually at temperatures above 650°C. The decomposition of benzene into carbon and hydrogen is a competing reaction at temperatures of about 750°C. Biphenyls are also formed when benzene and ethylene are heated to 130—160°C in the presence of alkali metals on activated A1203 (33). 

Silicon carbide is comparatively stable. The only violent reaction occurs when SiC is heated with a mixture of potassium dichromate and lead chromate. Chemical reactions do, however, take place between silicon carbide and a variety of compounds at relatively high temperatures. Sodium silicate attacks SiC above 1300°C, and SiC reacts with calcium and magnesium oxides above 1000°C and with copper oxide at 800°C to form the metal silicide. Silicon carbide decomposes in fused alkalies such as potassium chromate or sodium chromate and in fused borax or cryolite, and reacts with carbon dioxide, hydrogen, air, and steam. Silicon carbide, resistant to chlorine below 700°C, reacts to form carbon and silicon tetrachloride at high temperature. SiC dissociates in molten iron and the silicon reacts with oxides present in the melt, a reaction of use in the metallurgy of iron and steel (qv). The dense, self-bonded type of SiC has good resistance to aluminum up to about 800°C, to bismuth and zinc at 600°C, and to tin up to 400°C a new silicon nitride-bonded type exhibits improved resistance to cryolite. 

In agreement with the relative reactivities of the alkali hydroxides and carbonates towards hydrogen sulphide, it has been observed that the blackening of basic lead carbonate by the gas is due to the conversion into sulphide of the lead hydroxide only and not of the carbonate.6... 

Hydroxylamine-disulphonic Acid, N(0H)(S03H)2.—The alkali hydroxylamine-disulphonates may be prepared by the addition of the alkali hydrogen sulphite in concentrated aqueous solution to the alkali nitrite. They are also formed when excess of sulphur dioxide is passed through a solution containing the alkali nitrite and either the alkali carbonate or hydroxide. The presence of caustic alkali confers stability on the compound, whilst acids decompose it even in the cold, hydroxyl-amine monosulphonie acid being formed.6... 

The thiocarbonates of the alkali and alkaline earth metals are soluble in water. The alkali thiocarbonates are yellow in colour. In concentrated solution these salts are fairly stable, but in dilute solution they are gradually decomposed, forming the carbonate and hydrogen sulphide. 

Oxalo-niobates or niobo-oxalates correspond to the vanado-oxalates, and contain both oxalic acid and niobic add radicals in the complex anion. The only known series possesses the general formula 3R aO. Nb 205.6C203.a H20, where R stands for an alkali metal. The sodium, potassium and rubidium salts are prepared by fusing one molecular proportion of niobium pentoxide with three molecular proportions of the alkali carbonate in a platinum crucible. The aqueous extract of the melt jjs poured into hot oxalic add solution concentration and cooling, or addition of alcohol or acetone, then brings about precipitation of the complex salt. Comparison of the dectrical conductivity measurements of solutions of the alkali oxalo-niobates with those of the alkali hydrogen oxalates determined under the same conditions indicates that the oxalo-niobates are hydrolysed in aqueous solution, and that their anions contain a complex oxalo-niobic acid radical.6... 

Carbonates. Carbonic acid H CO, is present to the extent of (1.27 i of the total CO present in ihe solution that is formed by dissolving CO in H 0 ai room temperature. The CO may be expelled fully upon boiling. The solution reads with alkalis to form carbonates, e.g. sodium carbonate, sodium hydrogen carbonate, calcium carbonate, calcium hydrogen carbonate. The acid ionization constant usually cited for carbonic... 

In addition to zinc oxide, other sensitizers of photoxidation may be employed. The addition of sodium nitrite in the presence of moisture turns starch into lower dextrins when the material is irradiated with 355-nm light.256 Ruthenium(IV) and titanium(IV) oxides as well as platinum oxide, all in conjunction with aqueous solutions of starch, eventually produce (in the presence of alkali) hydrogen, carbon dioxide, and photoxidation products.257 The use of Methylene Blue has also been reported. These studies provide evidence that only the sensitizer, and not the starch, is sensitized.258... 

Palladium-carbon-catalyzed hydrogenation of (16) gave (24), and NaBH4 reduction of (22) gave (25), both receptors now containing a saturated linkage between the aza crown system and the ferrocenyl redox center. This methylene-ferrocene linkage was found to serve as an insulator both compounds (24) and (25) are totally electrochemically insensitive to the presence of any alkali metal cation. 

Without a solvent, by itself or with the addition of a little alkali Chiefly potassium carbonate also hydrogen, oxygen, carbon monoxide, and carbon dioxide. 

Solid test On heating some solid alkali hydrogen carbonate in a dry test-tube carbon dioxide is evolved ... 

Carbon nanotubes can be prepared using solvothermal reactions, - however, inherent decomposition of organic compounds into carbon and hydrogen is not yet utilized in the solvothermal synthesis of nanotubes, but hexachlorobenzene was reduced by alkali metal according to the following reaction ... 

Leaching with alkali always takes place at high temperatures, either under pressure (5 to 6 bar, 95 to 120°C) or at atmospheric pressure (75 to 80°C). The leaching agent used is sodium carbonate, sodium hydrogen carbonate or ammonium carbonate. Uranium(Vl) oxide is converted in this process into uranyl tricarbonato-complexes ... 

The features of CO2 reduction at a Cu electrode also depends remarkably on cationic species. Table 14 shows faradaic efficiencies of CO2 reduction at a Cu electrode in 0.1 M various alkali hydrogen-carbonate solutions at a constant current density 5.0 mA cm" Hydrogen formation is prevalent in the Li electrolyte. 

---