Nickel & compounds: Overview
Description
The vast majority of nickel is used in alloys and more than 3,000 nickel alloys have been identified. Nickel is used to make stainless steel and other metal alloys. Nickel is commonly alloyed with iron, copper (Monel), chromium, aluminium and zinc. Alloys are used in the making of metal coins and jewellery and, in industry, for making metal items. Nickel and nickel compounds are used for nickel electroplating, to colour ceramics, to make batteries, for permanent magnet materials, and as catalysts.
Nickel acetate is used mainly as a mordant in the textile industry, and as a hydrogenation catalyst. It is also used as an intermediate in the formation of other nickel compounds, as a sealer for anodised aluminium, and in nickel electroplating.
Nickel carbonate is used as a chemical intermediate for nickel oxide, nickel powder, and nickel catalysts. It serves in electric components, such as vacuum tubes and transistor cans. It is used as a catalyst to remove organic contaminants from wastewater or potable water. It is used in the preparation of coloured glass, in the manufacture of certain nickel pigments, as a neutralising compound in nickel electroplating solution, and in the preparation of many specialty nickel compounds.
Nickel hydroxide is used in nickel-cadmium batteries and as a chemical intermediary for nickel catalysts and nickel salts. The hydrogenation of finely powdered newspaper with a nickel hydroxide catalyst produces conversion in high yields of cellulose feed materials to liquid hydrocarbon fuels.
Nickel oxide is used in fuel cell electrodes, the production of active nickel catalysts, electroplating, and colouring and decolourising glass. It is also used in the manufacture of nickel salts which can be used to make refined nickel oxide. It is used in non-metallic resistance thermometers or thermistors, which are temperature-sensitive semiconducting ceramics.
Substance details
Substance name: Nickel and compounds
CASR number: 7440-02-0
Molecular formula: Ni
Synonyms: Raney alloy, Raney nickel, C.I. 77775.
Nickel compounds covered by this article include nickel acetate (CASR# 373-02-4), nickel carbonate (CASR# 3333-67-3), nickel chloride (CASR# 7718-54-9), nickel hydroxide (CAS #12054-48-7), nickel nitrate (CASR# 13138-45-9), nickel oxide (CAS #1313-99-1), and nickel sulfate (CASR# 7786-81-4). Nickel carbonyl and nickel subsulfide are treated separately in the NPI.
Physical properties
Nickel is a silvery-white, hard, malleable, ductile, ferromagnetic metal. It is a good conductor of electricity and heat.
Atomic Number: 28
Atomic Mass: 58.7
Melting Point: 1453°C
Boiling Point: 2732°C
Specific Gravity: 8.9
Properties vary widely depending on the particular compound. Some physical properties for selected nickel compounds follow.
Nickel acetate is a green powder that effloresces somewhat in air. It has a light acetic acid odour.
Nickel carbonate occurs as light green rhombic crystals or as a brown powder. It decomposes before it melts.
Nickel hydroxide occurs as either a fine green powder, green crystals, or an amorphous black powder. Its melting point is 230°C and its vapour density is 3.2.
Nickel oxide occurs as a green or black powder that becomes yellow when heated. Nickel oxide has a specific gravity of 6.7 and melts at 1960°C.
Nickel sulfate is a yellow-green crystalline solid. It decomposes when heated. Its specific gravity is 3.7.
Chemical properties
Nickel metal is relatively resistant to corrosion. It dissolves in dilute mineral acids and is insoluble in concentrated nitric acid.
Water solubility of nickel compounds vary. Nickel acetate, bromide, chloride, iodide, nitrate and sulfate are soluble in water. Hydrated nickel (II) is the primary ion in aqueous solutions. Nickel oxides, hydroxides, sulfides, arsenide, chromate, carbonate, phosphate and selenide are water-insoluble nickel compounds. More properties for selected nickel compounds follow.
Nickel oxide is soluble in acids, potassium cyanide, and ammonium hydroxide. It is insoluble in both cold and hot water, and caustic solutions. The black form of nickel oxide is chemically reactive, whereas the green nickel oxide form is inert and refractory.
Nickel acetate is soluble in acetic acid and water, and insoluble in alcohol. Nickel acetate decomposes before it melts, forming nickel oxide and emitting irritating fumes.
Nickel carbonate is soluble in dilute acids and ammonia, and insoluble in hot water. It can react violently with iodine, hydrogen sulfide, or a mixture of barium oxide and air.
Nickel hydroxide is soluble in acids and ammonium hydroxide, but is practically insoluble in water. It decomposes into nickel oxide and water when heated at elevated temperatures.
Further information
The National Pollutant Inventory (NPI) holds data for all sources of nickel and compounds emissions in Australia.
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