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| Names | |||
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| IUPAC name Nickel(II) sulfate | |||
| Other names Nickelous sulfate Nickel (II) sulphate | |||
| Identifiers | |||
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| ECHA InfoCard | 100.029.186 | ||
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| Properties | |||
| NiSO4 | |||
| Molar mass | 154.75 g/mol (anhydrous) 262.85 g/mol (hexahydrate) 280.86 g/mol (heptahydrate) | ||
| Appearance | yellow-green solid (anhydrous) turquoise crystals (hexahydrate) turquoise crystals (heptahydrate) | ||
| Odor | odorless | ||
| Density | 4.01 g/cm3 (anhydrous) 2.07 g/cm3 (hexahydrate) 1.948 g/cm3 (heptahydrate) | ||
| Melting point | 1210 °C (anhydrous, at high pressure) 53 °C (hexahydrate) | ||
| Boiling point | > 640 °C (anhydrous, decomposes) 100 °C (hexahydrate, decomposes) | ||
| 65 g/100 mL (20 °C) 77.5 g/100 mL (30 °C) (heptahydrate) | |||
| Solubility | anhydrous insoluble inethanol,ether,acetone hexahydrate insoluble inethanol,ammonia heptahydrate soluble inalcohol | ||
| Acidity (pKa) | 4.5 (hexahydrate) | ||
| +4005.0·10−6 cm3/mol | |||
Refractive index (nD) | 1.511 (hexahydrate) 1.467 (heptahydrate) | ||
| Structure | |||
| orthorombic (anhydrous) tetragonal (hexahydrate) rhombohedral (heptahydrate) | |||
| Hazards | |||
| GHS labelling: | |||
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| Danger | |||
| H302+H332,H315,H317,H334,H341,H350,H360D,H372,H410 | |||
| P201,P261,P273,P280,P308+P313,P501 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | Non-flammable | ||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose) | 264 mg/kg | ||
| Safety data sheet (SDS) | External MSDS | ||
| Related compounds | |||
Othercations | Cobalt(II) sulfate Copper(II) sulfate Iron(II) sulfate | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Nickel(II) sulfate, or justnickel sulfate, usually refers to theinorganic compound with theformula NiSO4(H2O)6. This highlysoluble turquoise colouredsalt is a common source of the Ni2+ion forelectroplating. Approximately 40,000tonnes were produced in 2005.[1]
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At least seven sulfate salts of nickel(II) are known. These salts differ in terms of theirhydration 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 yellowanhydrous form, NiSO4, crystallizes in orthorhombic crystal system[2] and in standard pressure decomposes toNiO in temperatures above 640 °C, before reaching themelting point.[3] It melts only at high system pressure, using a constant volume method the melting point was found to be 1210 °C.[4] The anhydrous sulfate is produced by heating the hydrates above 330 °C.
X-ray crystallography measurements show that NiSO4·6H2O consists of the octahedral[Ni(H2O)6]2+ ions. These ions in turn arehydrogen bonded to sulfate ions.[5] Dissolution of the salt in water gives solutions containing theaquo complex[Ni(H2O)6]2+.
All nickel sulfates areparamagnetic.
The salt is usually obtained as a by-product ofcopper refining. It can also be produced by dissolution of nickel metal or nickel oxides in sulfuric acid.
Aqueous solutions of nickel sulfate react with sodium carbonate to precipitatenickel carbonate, a precursor to nickel-based catalysts and pigments.[6] Addition ofammonium sulfate to concentrated aqueous solutions of nickel sulfate precipitatesNi(NH4)2(SO4)2·6H2O. This blue-coloured solid is analogous toMohr's salt,Fe(NH4)2(SO4)2·6H2O.[1]
Nickel sulfate has some uses in the laboratory. Columns used inpolyhistidine-tagging, useful inbiochemistry andmolecular biology, are regenerated with nickel sulfate. Aqueous solutions of NiSO4·6H2O and related hydrates react with ammonia to give[Ni(NH3)6]SO4 and withethylenediamine to give thecomplex[Ni(H2NCH2CH2NH2)3]SO4. The latter is occasionally used as a calibrant formagnetic susceptibility measurements because it has no tendency to hydrate.
Nickel sulfate occurs as the rare mineral retgersite,[7] which is ahexahydrate. The second hexahydrate is known as nickelhexahydrite(Ni,Mg,Fe)SO4·6H2O, which is the monoclinic dimorph of retgersite. The heptahydrate, which is relatively unstable in air, occurs as morenosite. The monohydrate occurs as the very rare mineral dwornikite(Ni,Fe)SO4·H2O.
In 2005–2006, nickel sulfate was the topallergen inpatch tests (19.0%).[8] Nickel sulfate is classified as a human carcinogen[9][10] based on increased respiratory cancer risks observed in epidemiological studies of sulfidic ore refinery workers.[11] In a 2-year inhalation study in F344 rats and B6C3F1 mice, there was no evidence of carcinogenic activity, although increased lung inflammations and bronchiallymph node hyperplasia were observed.[12] These results strongly suggest that there is a threshold for the carcinogenicity of nickel sulfate via inhalation. In a 2-year study with daily oral administration of nickel sulfate hexahydrate to F344 rats, no evidence for increased carcinogenic activity was observed.[13] The human and animal data consistently indicate a lack of carcinogenicity via the oral route of exposure and limit the carcinogenicity of nickel compounds to respiratory tumours after inhalation.[14] Whether these effects are relevant to humans is unclear as epidemiological studies of highly exposed female workers have not shown adverse developmental toxicity effects.[15]
