What Is Nickel Sulfate?
Nickel(II) sulfate is a sulfate of sulfuric acid with the composition NiSO4.
Nickel(II) sulfate is generally used to indicate the valence. In addition to anhydride, mono-, di-, tetra-, hexa-, and heptahydrate are also known.
CAS registration numbers are 7786-81-4 for anhydrous, 10101-97-0 for hexahydrate, and 10101-98-1 for heptahydrate.
Uses of Nickel Sulfate
Nickel sulfate is mainly used for electrolytic nickel plating, electroless nickel plating, nickel catalysts in general, catalytic agents, black colorants for zinc and brass, paints and varnishes, pigments for ceramics, catalysts in general, and aluminum-colored batteries.
Nickel sulfate is used as one of the materials for plating metals and surface treatments such as plastics because of its corrosion and wear resistance. Plating or surface treatment with nickel sulfate not only improves durability and wear resistance but can also alter technical or physical properties such as electrical conductivity.
In battery applications, nickel is also used for cathodes and in a variety of products in industries such as automobiles, aircraft, and electronics.
Properties of Nickel Sulfate
1. Basic Information on Nickel Sulfate (Anhydride)
Nickel sulfate anhydride has a molecular weight of 154.75, a melting point of over 100°C, a boiling point of 840°C, and a yellow solid appearance at room temperature. It has a density of 3.68 g/mL and is readily soluble in water, with aqueous solutions showing acidity (solubility: 650 g/L (20°C)). It is insoluble in organic solvents such as ethanol, ether, and acetone.
2. Basic Information on Nickel Sulfate (Hexahydrate)
Nickel sulfate hexahydrate NiSO4・6H2O has a molecular weight of 262.836, a melting point of 53°C, a boiling point of 100°C (decomposition), and a green crystal appearance at room temperature. It is readily soluble in ethanol and ammonia and is known to dissolve in water at 50°C. Its density is 2.07 g/mL.
Types of Nickel Sulfate
Nickel sulfate is mainly sold as an industrial metal or industrial nickel compound and as a reagent product for research and development.
1. Industrial Products
For industrial use, crystals are sold in 20 kg bags and other capacities, and solution products exist in concentrations such as 35% and 30%. Solution products are mainly supplied for replenishing the nickel component of watt baths.
Crystal products are used for nickel plating, including electroplating and electroless plating, and are also envisioned for applications other than plating, such as aluminum coloration, catalysts, and battery materials. Due to its many applications, the substance is sold by a variety of companies.
2. Reagent Products for Research and Development
Reagent products for research and development are available in 25g, 100g, 500g, and other capacities. Possible applications include nickel ion sources for analysis, raw materials for plating, and catalyst raw materials.
In addition to pure substances, some manufacturers sell 0.5 mol/L solutions as a standard solution for volumetric analysis. The substance is usually handled as a reagent product that can be stored at room temperature.
Other Information on Nickel Sulfate
1. Synthesis of Nickel Sulfate
Nickel sulfate is synthesized by the reaction of nickel sulfate with metallic nickel. Nickel(II) oxide, nickel(II) hydroxide, or nickel carbonate can be used instead of metallic nickel. Hydrogen is a byproduct of this reaction.
Nickel sulfate can also be obtained by the reaction of nickel sulfate and nickel oxide or nickel sulfate and nickel hydroxide (the byproduct is water).
2. Reactivity of Nickel Sulfate
Nickel sulfate is a nonflammable substance that decomposes when heated to form toxic sulfur trioxide and nickel(II) oxide.
Nickel sulfate weathers in air to a white powder, but returns to a green color when water is added. The hydrate loses four molecules at 100°C, six molecules at 103.3°C, and all water at 279.4°C.