Cobalt(II) sulfate is any of the
inorganic compounds with the formula CoSO
4(H
2O)
x. Usually cobalt sulfate refers to the hexa- or heptahydrates CoSO
4.6H
2O or CoSO
4.7H
2O, respectively.
[ The heptahydrate is a red solid that is soluble in water and methanol. Since cobalt(II) has an odd number of electrons, its salts are ]paramagnetic
Paramagnetism is a form of magnetism whereby some materials are weakly attracted by an externally applied magnetic field, and form internal, induced magnetic fields in the direction of the applied magnetic field. In contrast with this behavior, ...
.
Preparation, and structure
It forms by the reaction of metallic cobalt, its oxide, hydroxide, or carbonate with aqueous sulfuric acid:[
:Co + H2SO4 + 7 H2O → CoSO4(H2O)7 + H2
:CoO + H2SO4 + 6 H2O → CoSO4(H2O)7
The heptahydrate is only stable at humidity >70% at room temperature, otherwise it converts to the hexahydrate.][ The hexahydrate converts to the monohydrate and the anhydrous forms at 100 and 250 °C, respectively.][
:CoSO4(H2O)7 → CoSO4(H2O)6 + H2O
:CoSO4(H2O)6 → CoSO4(H2O) + 5H2O
:CoSO4(H2O) → CoSO4 + H2O
The hexahydrate is a ]metal aquo complex
In chemistry, metal aquo complexes are coordination compounds containing metal ions with only water as a ligand. These complexes are the predominant species in aqueous solutions of many metal salts, such as metal nitrates, sulfates, and perchlorat ...
consisting of octahedral
In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet a ...
o(H2O)6sup>2+ ions associated with sulfate
The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...
anions
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...
(see image in table). The monoclinic heptahydrate has also been characterized by X-ray crystallography
X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...
. It also features o(H2O)6sup>2+ octahedra as well as one water of crystallization
In chemistry, water(s) of crystallization or water(s) of hydration are water molecules that are present inside crystals. Water is often incorporated in the formation of crystals from aqueous solutions. In some contexts, water of crystallization i ...
.
Uses and reactions
Cobalt sulfates are important intermediates in the extraction of cobalt from its ores. Thus, crushed, partially refined ores are treated with sulfuric acid to give red-colored solutions containing cobalt sulfate.pigment
A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compou ...
s, as well as in the manufacture of other cobalt salts. Cobalt pigment is used in porcelains and glass. Cobalt(II) sulfate is used in storage batteries and electroplating baths, sympathetic inks, and as an additive to soils and animal feeds. For these purposes, the cobalt sulfate is produced by treating cobalt oxide with sulfuric acid.[
Being commonly available commercially, the heptahydrate is a routine source of cobalt in coordination chemistry.
]
Natural occurrence
Rarely, cobalt(II) sulfate is found in form of few crystallohydrate minerals, occurring among oxidation zones containing primary Co minerals (like skutterudite
Named after Skuterudåsen, a hill in Modum, Norway, skutterudite is a cobalt arsenide mineral containing variable amounts of nickel and iron substituting for cobalt with the ideal formula CoAs3. Some references give the arsenic a variable formula ...
or cobaltite
Cobaltite is a sulfide mineral composed of cobalt, arsenic, and sulfur, Co As S. Its impurities may contain up to 10% iron and variable amounts of nickel.Klein, Cornelus and Cornrlius Hurlbut, 1996, ''Manual of Mineralogy'', 20th ed., Wiley, p. ...
). These minerals are: biebierite (heptahydrate), moorhouseite (Co,Ni,Mn)SO4.6H2O,
Health issues
Cobalt is an essential mineral for mammals, but more than a few micrograms per day is harmful. Although poisonings have rarely resulted from cobalt compounds, their chronic ingestion has caused serious health problems at doses far less than the lethal dose. In 1965, the addition of a cobalt compound to stabilize beer foam in Canada led to a peculiar form of toxin-induced cardiomyopathy, which came to be known as ''beer drinker's cardiomyopathy''.
Furthermore, cobalt(II) sulfate is suspected of causing cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
(i.e., possibly carcinogen
A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive subs ...
ic, IARC Group 2B) as per the International Agency for Research on Cancer
The International Agency for Research on Cancer (IARC; french: Centre International de Recherche sur le Cancer, CIRC) is an intergovernmental agency forming part of the World Health Organization of the United Nations.
Its role is to conduct and ...
(IARC) Monographs.
Related compounds
* the Tutton salt K2Co(SO4)2
References
{{Sulfates
Cobalt(II) compounds
Sulfates
IARC Group 2B carcinogens
Hydrates