Nickel sulfate forms

The base was being prepared by distilling a mixture of hydroxylamine hydrochloride and sodium hydroxide in methanol under reduced pressure, and a violent explosion occurred towards the end of distillation [1], probably owing to an increase in pressure above 53 mbar. It explodes when heated under atmospheric pressure [2], Traces of hydroxylamine remaining after reaction with acetonitrile to form acetamide oxime caused an explosion during evaporation of solvent. Traces can be removed by treatment with diacetyl monoxime and ammoniacal nickel sulfate, forming nickel dimethylglyoxime [3], An account of an extremely violent explosion towards the end of vacuum distillation had been published previously [4], Anhydrous hydroxylamine is usually stored at 10°C to prevent internal oxidation-reduction reactions which occur at ambient temperature [5], See other REDOX REACTIONS... 

Nickel sulfate forms double salts with ammonium or alkali metal sulfates. For example, blue-green hydrated ammonium nickel sulfate, (NH4)2S04 NiS04 6H20, crystallizes from a mixed solution of nickel sulfate and ammonium sulfate. Such double sulfates are isomorphous to corresponding alkali metal or ammonium double sulfates of iron, cobalt, magnesium, zinc, and other bivalent metals. 

In the simplest type, water is bound to inorganic cations as part of a coordination complex. This type of water is denoted as water of crystallization and is common for inorganic compounds. For example, nickel sulfate forms a well-defined hexahydrate, where the waters of hydration are bound directly to the Ni(II) ion. Well-defined multiple hydrate species can also form with organic molecules, where the water molecules bridge unit cells in the overall structure. Finally, water molecules can exist in a semispecific manner, lining cavities within the crystal structure. This last hydrate type is often termed a channel hydrate. 

Ma.nufa.cture. The preferred method for making nickel sulfate is adding nickel powder to hot dilute sulfuric acid. Adding sulfuric acid to nickel powder in hot water enhances the formation of H2S. Hydrogen sulfide always forms as a by-product upon reaction of metallic nickel and sulfuric acid. The hberated hydrogen is absorbed by the metal and then reduces the sulfate anion to H2S. 

Nickel sulfate also is made by the reaction of black nickel oxide and hot dilute sulfuric acid, or of dilute sulfuric acid and nickel carbonate. The reaction of nickel oxide and sulfuric acid has been studied and a reaction induction temperature of 49°C deterrnined (39). High purity nickel sulfate is made from the reaction of nickel carbonyl, sulfur dioxide, and oxygen in the gas phase at 100°C (40). Another method for the continuous manufacture of nickel sulfate is the gas-phase reaction of nickel carbonyl and nitric acid, recovering the soHd product in sulfuric acid, and continuously removing the soHd nickel sulfate from the acid mixture (41). In this last method, nickel carbonyl and sulfuric acid are fed into a closed-loop reactor. Nickel sulfate and carbon monoxide are produced the CO is thus recycled to form nickel carbonyl. 

The scheme F involves sulphating roasting. The conditions are so chosen that iron is converted to its oxidic form (Fe203) while nickel and copper are converted to nickel sulfate and copper sulfate respectively. The product is subsequently water leached to take the sulfates into solution, leaving the iron oxide in the leach residue. 

The composition of the codeposition bath is defined not only by the concentration and type of electrolyte used for depositing the matrix metal, but also by the particle loading in suspension, the pH, the temperature, and the additives used. A variety of electrolytes have been used for the electrocodeposition process including simple metal sulfate or acidic metal sulfate baths to form a metal matrix of copper, iron, nickel, cobalt, or chromium, or their alloys. Deposition of a nickel matrix has also been conducted using a Watts bath which consists of nickel sulfate, nickel chloride and boric acid, and electrolyte baths based on nickel fluoborate or nickel sulfamate. Although many of the bath chemistries used provide high current efficiency, the effect of hydrogen evolution on electrocodeposition is not discussed in the literature. 

Nickel sulfate (NiSO ) exists in different states depending on its hydrated forms (where water molecules bond with ions in suspended substances). Nickel sulfate can be in the form of greenish-yellow, blue, or green crystals, depending upon the degree of hydration. It is used in nickel-plating iron and copper, as a catalyst, as a mordant in the textile industry, and as a coating for other substances. 

Nickel is a silver-white, lustrous, hard, malleable, ductile, ferromagnetic metal that is relatively resistant to corrosion and is a fair conductor of heat and electricity. Nickel is a ubiquitous trace metal that occurs in soil, water, air, and in the biosphere. The average content in the earth s crust is about 0.008%. Nickel ore deposits are accumulations of nickel sulfide minerals (mostly pentlandite) and laterites. Nickel exists in five major forms elemental nickel and its alloys inorganic, water-soluble compounds (e.g., nickel chloride, nickel sulfate, and nickel nitrate) inorganic, water-insoluble compounds (e.g., nickel carbonate, nickel sulfide, and nickel oxide) organic, water-insoluble compounds and nickel carbonyl Ni(CO). ... 

Three-dimensional epitaxial crystallites (TECs) were observed in the first stages of electrodeposition of copper (51) and nickel (58) on copper substrates. TECs of nickel formed on copper-film substrate from nickel sulfate solutions in low concentration are shaped rectangularly with edges averaging 1300 A in length. The coherent... 

NH4)2S04 forms many double salts (ammonium metal sulfates) when its solution is mixed with equimolar solutions of metal sulfates and the solution is slowly evaporated. Such double metal sulfates include ammonium cobal-tous sulfate, (NH4)2Co(S04)2 ferric ammonium sulfate, (NH4)2Fe(S04)2, ammonium nickel sulfate, (NH4)2Ni(S04)2 and ammonium cerous sulfate, NH4CeS04. 

Ammonium thiocyanate reacts with nickel sulfate and ammoniacal solution of hydrzine sulfate forming a violet-blue crystalline precipitate ... 

Several nickel salts are obtained by reactions of nickel oxide with mineral acids. Thus, the reaction of black nickel oxide with hot dilute sulfuric acid forms nickel sulfate, NiS04 6H2O. Similarly, dilute nitric acid, hydrochloric, and hydrobromic acids when heated react with the black form of nickel oxide to yield corresponding nickel salts as hexahydrates. 

Although most patch testing is done with nickel sulfate because it is less irritating than nickel chloride, exposure of the skin to nickel alloys results in the release of nickel chloride from the influence of human sweat. Therefore, nickel chloride is the more relevant form of nickel for examining threshold concentrations (Menne 1994). Menne and Calvin (1993) examined skin reactions to various concentrations of nickel chloride in 51 sensitive and 16 nonsensitive individuals. Although inflammatory reactions in the sweat ducts and hair follicles were observed at 0.01% and lower, positive reactions to nickel were not observed. To be scored as a positive reaction, the test area had to have both redness and infiltration, while the appearance of vesicles and/or a bullous reaction were scored as a more severe reaction. At 0.1%, 4/51 and 1/51 tested positive with and without 4% sodium lauryl sulfate. Menne et al. (1987) examined the reactivity to different nickel alloys in 173 nickel-sensitive individuals. With one exception (Inconel 600), alloys that released nickel into synthetic sweat at a rate of <0.5 pg/cmVweek showed weak reactivity, while alloys that released nickel at a rate of >1 pg/cm /week produced strong reactions. 

Nickel oxide also comes in a black crystalline form that has a slightly higher oxygen content than its formula, NiO (Antonsen 1981). The nickel content of black nickel oxide is 76-77% compared with 78.5% for the more stable green nickel oxide. Nickel sulfate, nickel chloride, and nickel nitrate usually exist as hexahydrates, while nickel acetate is generally in the form of a tetrahydrate. 

The form of nickel emitted to the atmosphere varies according to the type of source. Species associated with combustion, incineration, and metals smelting and refining are often complex nickel oxides, nickel sulfate, metallic nickel, and in more specialized industries, nickel silicate, nickel subsulfide, and nickel chloride (EPA 1985a). 

Little is known concerning the chemistry of nickel in the atmosphere. The probable species present in the atmosphere include soil minerals, nickel oxide, and nickel sulfate (Schmidt and Andren 1980). In aerobic waters at environmental pHs, the predominant form of nickel is the hexahydrate Ni(H20)g ion (Richter and Theis 1980). Complexes with naturally occurring anions, such as OH, SO/, and Cf, are formed to a small degree. Complexes with hydroxyl radicals are more stable than those with sulfate, which in turn are more stable than those with chloride. Ni(OH)2° becomes the dominant species above pH 9.5. In anaerobic systems, nickel sulfide forms if sulfur is present, and this limits the solubility of nickel. In soil, the most important sinks for nickel, other than soil minerals, are amorphous oxides of iron and manganese. The mobility of nickel in soil is site specific pH is the primary factor affecting leachability. Mobility increases at low pH. At one well-studied site, the sulfate concentration and the... 

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