Nickel sulfate

Nickel(II) sulfate

Anhydrous

Hexahydrate
Identifiers
CAS number 7786-81-4 YesY, (anhydrous)
10101-97-0 (hexahydrate)
10101-98-1 (heptahydrate)
PubChem 24586
ChemSpider 22989 YesY
UNII 4FLT4T3WUN YesY
EC number 232-104-9
ChEBI CHEBI:53001 YesY
RTECS number QR9600000
Jmol-3D images Image 1
Properties
Molecular formula NiSO4
Molar mass 154.75 g/mol (anhydrous)
262.85 g/mol (hexahydrate)
280.86 g/mol (heptahydrate)
Appearance yellow solid (anhydrous)
green-blue crystals (hexahydrate)
blue crystals (heptahydrate)
Odor odorless
Density 4.01 g/cm3 (anhydrous)
2.07 g/cm3 (hexahydrate)
1.948 g/cm3 (heptahydrate)
Melting point

> 100 °C (anhydrous)
53 °C (hexahydrate)

Boiling point

840 °C (anhydrous, decomp)
100 °C (hexahydrate, decomp)

Solubility in water 65 g/100 mL (20 °C)
77.5 g/100 mL (30 °C) (heptahydrate)
Solubility anhydrous
insoluble in ethanol, ether, acetone
hexahydrate
very soluble in ethanol, ammonia
heptahydrate
soluble in alcohol
Acidity (pKa) 4.5 (hexahydrate)
Refractive index (nD) 1.511 (hexahydrate)
1.467 (heptahydrate)
Structure
Crystal structure cubic (anhydrous)
tetragonal (hexahydrate)
rhombohedral (hexahydrate)
Hazards
MSDS External MSDS
EU Index 028-009-00-5
EU classification Carc. Cat. 1
Muta. Cat. 3
Repr. Cat. 2
Toxic (T)
Harmful (Xn)
Irritant (Xi)
Dangerous for the environment (N)
R-phrases R49, R61, R20/22, R38, R42/43, R48/23, R68, R50/53
S-phrases S53, S45, S60, S61
NFPA 704
0
2
0
Flash point Non-flammable
LD50 264 mg/kg
Related compounds
Other cations Cobalt(II) sulfate
Copper(II) sulfate
Iron(II) sulfate
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Nickel(II) sulfate, or just nickel sulfate, usually refers to the inorganic compound with the formula NiSO4(H2O)6. This highly soluble blue-coloured salt is a common source of the Ni2+ ion for electroplating. Approximately 40,000 tonnes were produced in 2005. It is mainly used for electroplating of nickel.[1]

Structures

At least seven sulfate salts of nickel(II) are known. These salts differ in terms of their hydration or crystal habit. The common tetragonal hexahydrate crystallizes from aqueous solution between 30.7 and 53.8 °C. Below these temperatures, a heptahydrate crystallises, and above these temperatures an orthorhombic hexahydrate forms. The yellow anhydrous form, NiSO4, is a high melting solid that is rarely encountered in the laboratory. This material produced by heating the hydrates above 330 °C. It decomposes at still higher temperatures to nickel oxide.[1]

X-ray crystallography measurements show that NiSO4·6H2O consists of the octahedral [Ni(H2O)6]2+ ions. These ions in turn are hydrogen bonded to sulfate ions.[2] Dissolution of the salt in water gives solutions containing the aquo complex [Ni(H2O)6]2+.

All nickel sulfates are paramagnetic.

Production, applications, and coordination chemistry

The salt is usually obtained as a by-product of copper refining. It is also produced by dissolution of nickel metal or nickel oxides in sulfuric acid.

Aqueous solutions of nickel sulfate reacts with sodium carbonate to precipitate nickel carbonate, a precursor to nickel-based catalysts and pigments.[3] Addition of ammonium sulfate to concentrated aqueous solutions of nickel sulfate precipitates Ni(NH4)2(SO4)2·6H2O. This blue-coloured solid is analogous to Mohr's salt, Fe(NH4)2(SO4)2·6H2O.[1]

Nickel sulfate is used in the laboratory. Columns used in polyhistidine-tagging, useful in biochemistry and molecular biology, are regenerated with nickel sulfate. Aqueous solutions of NiSO4·6H2O and related hydrates react with ammonia to give [Ni(NH3)6]SO4 and with ethylenediamine to give [Ni(H2NCH2CH2NH2)3]SO4. The latter is occasionally used as a calibrant for magnetic susceptibility measurements because it has no tendency to hydrate.

Natural occurrence

Nickel sulfate occurs as the rare mineral retgersite, which is a hexahydrate. The second hexahydrate is known as nickelhexahydrite(Ni,Mg,Fe)SO4·6H2O. The heptahydrate, which is relatively unstable in air, occurs as morenosite. The monohydrate occurs as very rare mineral dwornikite (Ni,Fe)SO4·H2O.

Safety

Nickel salts are carcinogenic and irritate the skin.

References

External links

  • International Chemical Safety Card 0063
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