Nickel sulfate

Physical Properties

Nickel sulfate (NiSO4) 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.
The anhydrous salt is a yellow cubic crystalline solid; density 3.68 g/cm3; decomposes at 848°C; readily dissolves in water; insoluble in ethanol, ether and acetone.
The hexahydrate, NiSO4•6H2O occurs in two crystalline forms, a blue tetragonal alpha-allotrope and an emerald green monoclinic beta form. The blue alpha form converts to green beta above 53.3°C. The beta form is isomorphous with magnesium sulfate hexahydrate, MgSO4•6H2O. Density of hexahydrate is 2.07 g/cm3; refractive index 1.511; loses water on heating; very soluble in water; also very soluble in ethanol and ammonia solution.
The heptahydrate, NiSO4•7H2O, forms green rhombohedral crystals; refractive index 1.467; density 1.948 g/cm3; loses water on heating; highly soluble in water (about 75 g/100mL at 15°C); soluble in alcohol.

nickel sulfate crystals

Uses

Nickel Sulfate is used to make other Nickel compounds, as a mordant, in dyeing and printing textiles, in nickel plating, in coloring metals, in ceramics and for producing driers for use in protective coatings.

Preparation

Nickel sulfate can be made by several methods. It is prepared by dissolving nickel metal, its oxide, or its carbonate in sulfuric acid. In such methods, powdered metal or black nickel oxide is added to hot dilute sulfuric acid, or nickel carbonate is added to dilute sulfuric acid at ambient temperature:
NiO + H2SO4 → NiSO4 + H2O
NiCO3 + H2SO4 → NiSO4 + CO2 + H2O
Impurities may be precipitated by treating the diluted solution with barium carbonate. Evaporation followed by cooling crystallizes hexahydrate in two modifications: blue tetragonal crystals obtained between 31.5 and 53.3°C, and above 53.3°C green monoclinic crystals form. The heptahydrate, NiSO4•7H2O, crystallizes at ordinary temperatures from pure aqueous solutions.
Nickel sulfate also can be produced in large-scale by gas phase reaction of nickel tetracarbonyl, sulfur dioxide, and oxygen at 100°C:
Ni(CO)4 + SO2 + O2 → NiSO4 + 4CO

Reactions

Hydrated nickel sulfate on heating at 103°C loses all of its water molecules. At 848°C, the anhydrous sulfate decomposes to nickel oxide and sulfur trioxide: NiSO4 → NiO + SO3
Nickel sulfate is used in preparing many insoluble nickel salts. In aqueous solutions, such insoluble nickel compounds precipitate; e.g.,
3Ni2+ + 3PO43¯ → Ni3(PO4)2
Nickel sulfate forms double salts with ammonium or alkali metal sulfates. For example, blue-green hydrated ammonium nickel sulfate, (NH4)2SO4•NiSO4•6H2O, 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.

Description

Nickel sulphate appears as blue to blue-green transparent crystals and is an odourless soluble nickel salt. Nickel sulphate is incompatible with strong acids. Nickel sulphate has extensive industrial applications in nickel patch testing, in nickel plating, as a raw material for the production of catalysts, in dyeing and printing fabrics as a mordant, and for blackening zinc and brass and in jewellery manufacture.

Chemical Properties

Nickel sulfate is a blue to blue-green crystalline solid. It has a sweet taste (do not test).

Chemical Properties

(1) Yellow-green crystals, (2) blue or emerald green crystals, (3) green crystals.All the sulfates are soluble in water; (2) and (3) are soluble in alcohol; (1) is insoluble in alcohol and ether.

Occurrence

Nickel sulfate heptahydrate occurs in nature as the mineral morenosite.Probably, the most important uses of nickel sulfate are as an electrolyte in nickel plating and electrorefining. Nickel sulfate also is used as a mordant in dyeing and printing textiles. Other uses are in the preparation of many nickel compounds and nickel catalysts; as a reducing agent; for imparting nickel coating or flashing on steel surface; and for blackening zinc and brass.

Uses

Nickel sulfate (NiSO4) 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.

Uses

Manufacture of nickel ammonium sulfate, nickel catalysts, nickel plating, mordant in dyeing and printing textiles, coatings, ceramics.

Definition

ChEBI: A metal sulfate having nickel(2+) as the metal ion.
Nickel sulfate, NiS04, is either yellow-green crystals which are soluble in water and insoluble in alcohol and ether,or blue,emerald-green, or green crystals which are soluble in water and alcohol. Derivation is by action of sulfuric acidonnickel. Used in the manufacture of nickel ammonium sulfate, nickel catalysts, nickel plating, and as a mordant in dyeing and printing textiles, coatings,and ceramics.

General Description

Anhydrous Nickel sulfate is a yellow-green crystalline solid. Nickel sulfate can also be obtained as a hexahydrate (NiSO4.6H2O (CAS: 10101-97-0) which is blue to emerald green, and as a heptahydrate (NiSO4.7H2O) (CAS: 10101-98-1) , which is green. Samples can contain variable quantities of water, depending on their previous exposure to moisture or conditions. All forms are mildly toxic and are carcinogenic. All are denser than water. The primary hazard is the threat to the environment. Immediate steps should be taken to limit its spread to the environment. Used to make other nickel compounds, in printing, and in dyeing of textiles.

Air & Water Reactions

Water soluble yielding acidic corrosive water solutions.

Reactivity Profile

Gives an acidic solution when dissolved in water. Emits highly toxic fumes of metallic nickel, oxides of sulfur, and oxides of nitrogen when heated to decomposition [Lewis, 3rd ed., 1993, p. 910].

Hazard

Toxic material. Questionable carcinogen.

Health Hazard

Dermatitis.

Flammability and Explosibility

Non flammable

Industrial uses

Nickel sulfate is the most widely used salt for nickel-plating baths, and is known in the plating industry as single nickel salt. It is easily produced by the reaction of sulfuric acid on nickel, and comes in pea-green water-soluble crystalline pellets of the compositionNiSO₄.7H₂O, of a specific gravity of 1.98, melting at about 100 C. Double nickel salt is nickel ammonium sulfate,NiSO₄.(NH₄)₂.SO₄.6H₂O , used especially for plating on zinc. To produce a harder and whiter finish in nickel plating, cobaltous sulfamate, a water-soluble powder of the composition Co(NH₂SO₃)₂.3H₂O, is used with the nickel sulfate. Nickel plate has a normal hardness of Brinell 90 to 140, but by controlled processes file-hard plates can be obtained from sulfate baths. In electroless plating, nickel sulfate, a reducing agent, a pH adjuster, and complexing and stabilizing agents are combined to deposit metallic nickel on an immersed object.The electroless nickel coating is comparable to electrolytic chrome.

Safety Profile

Confirmed human carcinogen with experimental tumorigenic data. Poison by intravenous, intraperitoneal, and subcutaneous routes. Human mutation data reported. A human skin irritant. When heated to decomposition it emits very toxic fumes of SOx. See also NICKEL COMPOUNDS and SULFATES.

Potential Exposure

Nickel sulfate is used in plating baths, and as an intermediate in the production of nickel ammonium sulfate; as a mordant in dyeing, and printing textiles; coatings, and ceramics.

Shipping

UN3077 Environmentally hazardous substances, solid, n.o.s., Hazard Class: 9; Labels: 9-Miscellaneous hazardous material, Technical Name Required. UN3288 Toxic solids, inorganic, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name Required.

Incompatibilities

A strong reducing agent. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. The aqueous solution is a weak acid. Sulfates may react violently with aluminum, magnesium.

Waste Disposal

Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal.