Nickel ii sulfate heptahydrate is one of the common chemical compounds found in nature. It is soluble in water, and is used in the preparation of nickel catalysts and pigments. It is also a good ultraviolet filter material.
It is derived from nickel oxide by dissolving it in sulphuric acid. The concentrated solution is then heated to form crystalline nickel sulfate hexahydrate.
This is a toxic and carcinogenic compound due to its fumes. It is the precursor to nickel electroplating, and it is used in biochemistry as a magnetic susceptibility calibrant.
When it is dissolved in water, it forms an acidic corrosive solution, emitting sulfur dioxide emissions on corrosion and nitrous oxide fumes when the solution is decomposed. As its aqueous solution is acidic, the pH value is 4.5 and it is incompatible with strong acids.
Aqueous solutions of nickel sulfate react with alkali metals or ammonium sulfates to produce double by-products in the form of isomorphous salts. These include Ni(NH4)2(SO4)2*6H2O, a blue-coloured solid that is similar to Mohr’s salt, Fe(NH4)2(SO4)2*6H2O.
The blue crystalline compound is the precursor to nickel carbonate, which is an important starting material in the preparation of many catalysts and pigments. It is also used as a reducing agent in the flashing of steel surfaces.
It is used as an aqueous electrolyte in surface finishing processes of metals. It is also a good mordant for dyeing and printing metals and textiles, as well as in the fabrication of organic nickel salts.