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Cobalt(II) sulfate
Names
	IUPAC name Cobalt(II) sulfate
	Other names Cobaltous sulfate
Identifiers
CAS Number	10124-43-3 ; 13455-34-0 (monohydrate) ; 10026-24-1 (heptahydrate) ;
3D model (JSmol)	anhydrous: Interactive image; hexahydrate: Interactive image; heptahydrate: Interactive image;
ChEBI	CHEBI:53470 ;
ChemSpider	23338 ;
ECHA InfoCard	100.030.291
EC Number	233-334-2;
KEGG	C17383; C19215 (heptahydrate);
PubChem CID	24965;
RTECS number	GG3100000 (anhydrous) ; GG3200000 (heptahydrate);
UNII	H7965X29HX ; Y8N698ZE0T (heptahydrate) ;
CompTox Dashboard (EPA)	DTXSID1031042 ;
	InChI InChI=1S/Co.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2 Key: KTVIXTQDYHMGHF-UHFFFAOYSA-L ; InChI=1/Co.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2 Key: KTVIXTQDYHMGHF-NUQVWONBAJ;
	SMILES anhydrous: [Co+2].[O-]S([O-])(=O)=O; hexahydrate: [OH2+][Co-4]([OH2+])([OH2+])([OH2+])([OH2+])[OH2+].[O-]S(=O)(=O)[O-]; heptahydrate: [OH2+][Co-4]([OH2+])([OH2+])([OH2+])([OH2+])[OH2+].[O-]S(=O)(=O)[O-].O;
Properties
Chemical formula	CoSO4·(H2O)n (n=0,1,6,7)
Molar mass	154.996 g/mol (anhydrous) ; 173.01 g/mol (monohydrate) ; 263.08 g/mol (hexahydrate) ; 281.103 g/mol (heptahydrate)
Appearance	reddish crystalline (anhydrous, monohydrate) ; pink salt (hexahydrate)
Odor	odorless (heptahydrate)
Density	3.71 g/cm3 (anhydrous) ; 3.075 g/cm3 (monohydrate) ; 2.019 g/cm3 (hexahydrate) ; 1.948 g/cm3 (heptahydrate)
Melting point	735 °C (1,355 °F; 1,008 K)
Solubility in water	anhydrous: ; 36.2 g/100 mL (20 °C) ; 38.3 g/100 mL (25 °C) ; 84 g/100 mL (100 °C) heptahydrate: ; 60.4 g/100 mL (3 °C) ; 67 g/100 mL (70 °C)
Solubility	anhydrous: ; 1.04 g/100 mL (methanol, 18 °C) ; insoluble in ammonia heptahydrate: ; 54.5 g/100 mL (methanol, 18 °C)
Magnetic susceptibility (χ)	+10,000·10−6 cm3/mol
Refractive index (nD)	1.639 (monohydrate) ; 1.540 (hexahydrate) ; 1.483 (heptahydrate)
Structure
Crystal structure	orthorhombic (anhydrous) ; monoclinic (monohydrate, heptahydrate)
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H302, H317, H334, H341, H350, H360, H410
Precautionary statements	P201, P202, P261, P264, P270, P272, P273, P280, P281, P285, P301+P312, P302+P352, P304+P341, P308+P313, P321, P330, P333+P313, P342+P311, P363, P391, P405, P501
NFPA 704 (fire diamond)	2 0 0
Flash point	Non-flammable
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	424 mg/kg (oral, rat)
Safety data sheet (SDS)	ICSC 1396 (heptahydrate)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Cobalt(II) sulfate is any of the inorganic compounds with the formula CoSO₄(H₂O)_x. Usually cobalt sulfate refers to the hexa- or heptahydrates CoSO₄^.6H₂O or CoSO₄^.7H₂O, respectively.^[1] 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.

Preparation, and structure

It forms by the reaction of metallic cobalt, its oxide, hydroxide, or carbonate with aqueous sulfuric acid:^[1]

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.^[2] The hexahydrate converts to the monohydrate and the anhydrous forms at 100 and 250 °C, respectively.^[1]

CoSO₄(H₂O)₇ → CoSO₄(H₂O)₆ + H₂O

CoSO₄(H₂O)₆ → CoSO₄(H₂O) + 5 H₂O

CoSO₄(H₂O) → CoSO₄ + H₂O

The hexahydrate is a metal aquo complex consisting of octahedral [Co(H₂O)₆]²⁺ ions associated with sulfate anions (see image in table).^[3] The monoclinic heptahydrate has also been characterized by X-ray crystallography. It also features [Co(H₂O)₆]²⁺ octahedra as well as one water of crystallization.^[2]

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.^[1]

Hydrated cobalt(II) sulfate is used in the preparation of pigments, 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.^[1]

Being commonly available commercially, the heptahydrate is a routine source of cobalt in coordination chemistry.^[4]

Natural occurrence

Rarely, cobalt(II) sulfate is found in form of few crystallohydrate minerals, occurring among oxidation zones containing primary Co minerals (like skutterudite or cobaltite). These minerals are: biebierite (heptahydrate), moorhouseite (Co,Ni,Mn)SO₄^.6H₂O,^[5]^[6] aplowite (Co,Mn,Ni)SO₄^.4H₂O and cobaltkieserite (monohydrate).^[7]^[8]^[6]

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.^[9]^[10]^[11]

Furthermore, cobalt(II) sulfate is suspected of causing cancer (i.e., possibly carcinogenic, IARC Group 2B) as per the International Agency for Research on Cancer (IARC) Monographs.^[12]