Zinc salt, thermal decomposition

Lai, M. and Howe, A. T. 1981a. Studies of zinc-chromium hydroxy salts. Thermal decomposition of [Zn2Cr(OH)g]X.nH20, where X = F", Cl, Br, r,l/2C03 and NO3. J. Solid State Chem. 39 368-76. 

The zinc oxide used in ZOE cements differs entirely from that used in zinc phosphate cements. Whereas the latter has to be ignited to a very high temperature to deactivate it, the opposite is true of the zinc oxides used in the ZOE cement, which are of an activated variety. They are normally prepared by the thermal decomposition of zinc salts at 350 °C to 450 °C such oxides are yellow. Zinc oxides prepared by oxidizing zinc in oxygen may also be used these are white. 

Zinc oxide is made either by the oxidation of the metal in oxygen (the indirect, IP, or French process), by the direct decomposition of zinc ores in air (the direct or American process) or by the thermal decomposition of zinc salts (TD zinc oxide). IP zinc oxides differ from TD zinc oxides in that their surfaces do not contain absorbed water. Also, whereas TD zinc oxide reacts with plain eugenol, IP zinc oxide hardly reacts unless activated by an acetic add or zinc acetate accelerator (Table 9.2). 

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... 

Magnesium reacts with incandescence on heating with cadmium cyanide, cobalt cyanide, copper cyanide, lead cyanide, nickel cyanide and zinc cyanide. With gold cyanide or mercury cyanide, the cyanogen released by thermal decomposition of these salts reacts explosively with magnesium. 

Various active nickel catalysts obtained not via reduction of nickel oxide with hydrogen have been described in the literature. Among these are the catalysts obtained by the decomposition of nickel carbonyl 10 by thermal decomposition of nickel formate or oxalate 11 by treating Ni-Si alloy or, more commonly, Ni-Al alloy with caustic alkali (or with heated water or steam) (Raney Ni) 12 by reducing nickel salts with a more electropositive metal,13 particularly by zinc dust followed by activation with an alkali or acid (Urushibara Ni) 14-16 and by reducing nickel salts with sodium boro-hydride (Ni boride catalyst)17-19 or other reducing agents.20-24... 

While many studies have been carried out aimed at the feedstock recycling of rubber wastes by pyrolysis and hydrogenation processes (see Chapters 5 and 7), little information is found on the catalytic cracking and reforming of rubber alone. Larsen35 has disclosed that waste rubber, such as used tyres, can be degraded in the presence of molten salt catalysts with properties as Lewis acids, such as zinc chloride, tin chloride and antimony iodide. The decomposition proceeds at temperatures between 380 and 500 °C to yield gases, oil and a residue, in proportions similar to those obtained by simple thermal decomposition. 

The aspect of the chemistry of the organophosphorodithioate salts most meaningful for their additive action involves their reaction with metals. Luther and Sinha [51] did not find any significant influence of the substrate metals on the thermal decomposition of isomeric zinc dibutyl phosphorodithioates over iron or silver. On the other hand, careful studies by Baumgarten [53] demonstrate the chemisorption of dialkylphosphorodithioate salts on metal, either powder or as evaporated film. Of particular interest are the findings for zinc diisopropyl phos-phorodithioate triply tagged with the radioactive elements Zn, and... 

ACETIC ACID, ZINC SALT (557-34-6 5970-45-6, dihydrate) Zn(CjH302)2 Zn(C2H302)2 2H20 Noncombustible solid. Moisture may cause hydrolysis or deconq)osition. Aqueous solution is a base. Incompatible with strong oxidizers, acids, oleum, strong bases. Thermal decomposition above 1472°F/800°C releases oxides of zinc and carbon and acetic acid fumes. 

Solid phosphites and hypophosphites both give phosphine on heating, which is readily recognised in very small concentrations by its smell. The thermal decomposition of the solid sodium salts can be represented approximately by Equations 14.5 and 14.6. Powdered zinc, when added to an acid solution of a phosphite or hypophosphite, will also cause evolution of phosphine. 

Shlyakhtin OA., Vinokurov A.L., Baranov A.N., Tretyakov Y.D. Direct synthesis of Bi-2212 by thermal decomposition of salt precursors. J. Supacond. 1998 11 507-514 SUeo E.E., Rotelo R., Jacobo S.E. Nickel zinc ferrites prepared by the citrate precursor method. Physica B 2002 320 257-260... 

To prevent the thermal decomposition of PVC with the consequent evolution of hydrogen chloride, stabilisers such as barium, cadmium, zinc, or calcium salts of fatty acids, and organotin compoimds or organophosphites are used to act as acid acceptors. 

Several octahedral dihydrazine metal (II) salts of this class were prepared and thermally decomposed. The succinates and malonates of nickel and cadmium decomposed explosively [1]. A later paper on mixed metal bis-hydrazine malonates of cobalt with magnesium, manganese, nickel, zinc or cadmium recommends that decomposition, in a pre-heated crucible at 500°C, be of small quantities only. The same workers have reported exothermic decomposition of similar hydrazine complexed salts of other small organic acids. 

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