Cobalt(II) sulfate

Cobalt(II) sulfate ;
Names:	cobalt sulfate; cobalt(II) sulfate; cobaltous sulfate; red vitriol;
Formula:	CoSO4 (anhydrous); CoSO4 · H2O (monohydrate); CoSO4 · 6H2O (hexahydrate); CoSO4 · 7H2O (heptahydrate);
Molar mass:	154.994 g/mol (anhydrous); 173.009 g/mol (monohydrate); 263.083 g/mol (hexahydrate); 281.098 g/mol (heptahydrate);
Density:	3.71 g/cm3 (anhydrous); 3.075 g/cm3 (monohydrate); 2.019 g/cm3 (hexahydrate); 1.948 g/cm3 (heptahydrate);
Crystal system:	monoclinic (heptahydrate); α=90°, γ=90°; monoclinic (hexahydrate); a=10.006 Å, b=7.252 Å, c=24.122 Åα=90°, β=98.96°, γ=90°;
Shapes:	https://en.crystalls.info/w/uploads/media/b/bc/Rhombic_prism.json Rhombic prism https://en.crystalls.info/w/uploads/media/3/35/Deformed_tetragonal_bipyramid.json Deformed tetragonal bipyramid ;
Color:	red; dark-red;
Melting point:	420 °C693.15 K <br />788 °F <br />1,247.67 °R <br /> (anhydrous);
Decomposition point:	71 °C344.15 K <br />159.8 °F <br />619.47 °R <br /> (heptahydrate); 96.8 °C369.95 K <br />206.24 °F <br />665.91 °R <br /> (hexahydrate); 250 °C523.15 K <br />482 °F <br />941.67 °R <br /> (monohydrate); 735 °C1,008.15 K <br />1,355 °F <br />1,814.67 °R <br /> (anhydrous);
Refractive index:	1.639 (monohydrate); 1.540 (hexahydrate); 1.483 (heptahydrate);
Magnetic properties:	paramagnetic; χ=1.00 · 10-2cm³/mol;
Stability:	erodes (heptahydrate); stable (hexahydrate); hygroscopic (anhydrous);
Toxicity:	moderately toxic; LD50=424mg/kg

Description

Inorganic compound, salt of bivalent transitional metal cobalt and inorganic sulfuric acid. From water solutions crystallizes as hexahydrate, heptahydrate and monohydrate.

Minerals

Occurs in nature as moorhouseite, bieberite and cobaltkieserite minerals.

Precursors

Reaction between cobalt(II) carbonate, hydroxide or oxide, and sulfuric acid

Chemical equation:

H₂SO₄ + CoCO₃ = CoSO₄ + H₂O + CO₂↑

H₂SO₄ + Co(OH)₂ = CoSO₄ + 2H₂O

H₂SO₄ + CoO = CoSO₄ + H₂O

For preparation of 100.00g of cobalt(II) sulfate

hexahydratehexahydrate
heptahydrate
monohydrate
anhydrous

а 45.21g of carbonate or 35.33g of hydroxide or 28.48g of oxide and 100.76g of 37%37% sulfuric acid is required.

Add acid to the flask, then add small parts of cobalt compound with stirring until it will totally dissolve or, if you use carbonate, until carbon dioxide emission will stop. After reaction will stop, filter the solution and use it for crystal growing.

Reaction between pure cobalt and sulfuric acid

Chemical equation:

H₂SO₄ + Co = CoSO₄ + H₂↑

For preparation of 100.00g of cobalt(II) sulfate

hexahydratehexahydrate
heptahydrate
monohydrate
anhydrous

а 22.40g of cobalt and 100.76g of 37%37% sulfuric acid is required.

Add hot acid solution to the flask, then add cobalt pieces, shavings or powder and stir and heat it until gas emission will stop.

This reaction is slow compared to the reaction with copper sulfate, due to oxidizing power difference.

Reaction between pure cobalt and copper(II) sulfate

Chemical equation:

CuSO₄ + Co = CoSO₄ + Cu;

For preparation of 100.00g of cobalt(II) sulfate

hexahydratehexahydrate
heptahydrate
monohydrate
anhydrous

а 22.40g of cobalt and 60.67g of copper(II) sulfate is required.

Add copper(II) sulfate solution to the flask, then add cobalt pieces, shavings or powder and leave for a few days. After solution color changing will stop, less active metal will completely displace into the precipitate. Then filter the solution.

If cobalt powder is used, then reaction is very quick and heat produced may even boil the solution. Addition of some sulfuric acid might be needed to destroy the oxide layer.

Influence of temperature

Growing at room temperature produces unstable heptahydrate while growing from a warm solution (60+ °C) produces a hexahydrate

Storage conditions

For crystal storing use hermetic vessel with small amount of saturated solution at the bottom or place wadding moistened with such solution. You can use such alternatives as vessel with vaseline or vegetable oil, organic non-hygroscopic solvent (kerosene, benzine or paraffin). Also you can use acrylate polymer or another kinds of solidifying plastic.

Solubility

TableGraph

Temperature	гр/`100,00` гр water		гр/`100,00` гр ethanol	гр/`100,00` гр methanol		гр/`100,00` гр ethylene glycol
Temperature	(anhydrous)	(heptahydrate)	(anhydrous)	(anhydrous)	(heptahydrate)	(anhydrous)
0°C273.15 K <br />32 °F <br />491.67 °R <br />	`25.5`
3°C276.15 K <br />37.4 °F <br />497.07 °R <br />		`60.4`
10°C283.15 K <br />50 °F <br />509.67 °R <br />	`30.5`
15°C288.15 K <br />59 °F <br />518.67 °R <br />			`0.017`	`0.3`
18°C291.15 K <br />64.4 °F <br />524.07 °R <br />					`54.5`
20°C293.15 K <br />68 °F <br />527.67 °R <br />	`36.2`					`33`
25°C298.15 K <br />77 °F <br />536.67 °R <br />	`38.3`		`0.018`	`0.418`
30°C303.15 K <br />86 °F <br />545.67 °R <br />	`41.8`
35°C308.15 K <br />95 °F <br />554.67 °R <br />				`0.419`
40°C313.15 K <br />104 °F <br />563.67 °R <br />	`48.8`
45°C318.15 K <br />113 °F <br />572.67 °R <br />			`0.023`	`0.372`
55°C328.15 K <br />131 °F <br />590.67 °R <br />			`0.026`	`0.267`
60°C333.15 K <br />140 °F <br />599.67 °R <br />	`~60`
70°C343.15 K <br />158 °F <br />617.67 °R <br />		`67`
80°C353.15 K <br />176 °F <br />635.67 °R <br />	`~70`

Highly soluble in glycerol. Insoluble in ethyl acetate, acetic acid, ammonia and benzonitrile.

Gallery

Sources

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Cobalt compounds
Salts	Cobalt(II) chloride (CoCl₂) • Cobalt(II) nitrate (Co(NO₃)₂) • Cobalt(II) oxalate (CoC₂O₄) • Cobalt(II) sulfate (CoSO₄) • Cobalt(II) tartrate (CoC₄H₄O₆)
Double salts	Cerium(III)-cobalt nitrate (3Co(NO₃)₂ · 2Ce(NO₃)₃) • Cerium(III)-cobalt-manganese nitrate (3(Co,Mn)(NO₃)₂ · 2Ce(NO₃)₃) • Cobalt(II)-ammonium sulfate ((NH₄)₂Co(SO₄)₂) • Cobalt(III)-ammonium sulfate (NH₄Co(SO₄)₂) • Cobalt(II)-potassium sulfate (K₂Co(SO₄)₂)
Complexes	Cyanocobalamin (C₆₃H₈₈CoN₁₄O₁₄P) • Hexamminecobalt(III) chloride ([Co(NH₃)₆]Cl₂) • Hexanitrocobaltates • Hexacyanocobaltates • Trioxalatocobaltates

Sulfates
Simple	Aluminum sulfate (Al₂(SO₄)₃) • Ammonium sulfate ((NH₄)₂SO₄) • Calcium sulfate (CaSO₄) • Cadmium sulfate (CdSO₄) • Cerium(III) sulfate (Ce₂(SO₄)₃) • Cerium(IV) sulfate (Ce(SO₄)₂) • Chromium(III) sulfate (Cr₂(SO₄)₃) • Cobalt(II) sulfate (CoSO₄) • Copper(II) sulfate (CuSO₄) • Gadolinium sulfate (Gd₂(SO₄)₃) • Holmium sulfate (Ho₂(SO₄)₃) • Hydrazine sulfate (N₂H₄ · H₂SO₄) • Iron(II) sulfate (FeSO₄) • Iron(III) sulfate (Fe₂(SO₄)₃) • Lanthanum sulfate (La₂(SO₄)₃) • Lithium sulfate (Li₂SO₄) • Magnesium sulfate (MgSO₄) • Manganese(II) sulfate (MnSO₄) • Neodymium sulfate (Nd₂(SO₄)₃) • Nickel sulfate (NiSO₄) • Potassium sulfate (K₂SO₄) • Praseodymium(III) sulfate (Pr₂(SO₄)₃) • Rubidium sulfate (Rb₂SO₄) • Sodium hydrosulfate (NaHSO₄) • Sodium sulfate (Na₂SO₄) • Yttrium sulfate (Gd₂(SO₄)₃) • Zinc sulfate (ZnSO₄)
Alums	Aluminum-ammonium sulfate (NH₄Al(SO₄)₂) • Aluminum-potassium sulfate (KAl(SO₄)₂) • Chromium(III)-ammonium sulfate (NH₄Cr(SO₄)₂) • Chromium(III)-potassium sulfate (KCr(SO₄)₂) • Cobalt(III)-ammonium sulfate (NH₄Co(SO₄)₂) • Indium(III)-potassium sulfate (KIn(SO₄)₂) • Iron(III)-ammonium sulfate (NH₄Fe(SO₄)₂) • Iron(III)-potassium sulfate (KFe(SO₄)₂) • Manganese(III)-ammonium sulfate (NH₄Mn(SO₄)₂) • Vanadium(III)-ammonium sulfate (NH₄V(SO₄)₂)
Tutton's salts	Chromium(II)-ammonium sulfate ((NH₄)₂Cr(SO₄)₂) • Cobalt(II)-ammonium sulfate ((NH₄)₂Co(SO₄)₂) • Cobalt(II)-potassium sulfate (K₂Co(SO₄)₂) • Copper(II)-ammonium sulfate ((NH₄)₂Cu(SO₄)₂) • Copper(II)-potassium sulfate (K₂Cu(SO₄)₂) • Iron(II)-ammonium sulfate ((NH₄)₂Fe(SO₄)₂) • Iron(II)-potassium sulfate (K₂Fe(SO₄)₂) • Magnesium-ammonium sulfate ((NH₄)₂Mg(SO₄)₂) • Magnesium-potassium sulfate (K₂Mg(SO₄)₂) • Magnesium-potassium sulfate-chromate (K₂CrO₄ · MgSO₄) • Manganese(II)-ammonium sulfate ((NH₄)₂Mn(SO₄)₂) • Manganese(II)-potassium sulfate (K₂Mn(SO₄)₂) • Nickel-ammonium sulfate ((NH₄)₂Ni(SO₄)₂) • Nickel-potassium sulfate (K₂Ni(SO₄)₂) • Vanadium(II)-ammonium sulfate ((NH₄)₂V(SO₄)₂) • Zinc-ammonium sulfate ((NH₄)₂Zn(SO₄)₂) • Zinc-potassium sulfate (K₂Zn(SO₄)₂) •
Double salts	Copper(II)-iron(II) sulfate ((Cu,Fe)SO₄) • Iron(II)-magnesium sulfate ((Fe,Mg)SO₄) • Lithium-potassium sulfate (KLiSO₄) • Sodium-ammonium sulfate (NaNH₄SO₄) • Zinc-sodium sulfate (Na₂Zn(SO₄)₂) •
Adducts	Triglycine sulfate ((NH₂CH₂COOH)₃ · H₂SO₄) • Glutamic acid sulfate (C₅H₉NO₄ · H₂SO₄)
Complexes	Cerium(III) sulfocerate(IV) (Ce₄[Ce(SO₄)₄]₃) • Glycinecopper(II) sulfate ([Cu(NH₂CH₂COOH)]SO₄) • Hexakarbamatzinc sulfate ([(CON₂H₄)₆Zn]SO₄) • Tetraamminecopper(II) sulfate ([Cu(NH₃)₄]SO₄) • Tris(hydroxymethil)methanoaminecopper(II) sulfate ([Cu(NH₂C(CH₂OH)₃)₄]SO₄)

Cobalt(II) sulfate
Names:	cobalt sulfate cobalt(II) sulfate cobaltous sulfate red vitriol
Formula:	CoSO₄ (anhydrous) CoSO₄ · H₂O (monohydrate) CoSO₄ · 6H₂O (hexahydrate) CoSO₄ · 7H₂O (heptahydrate)
Molar mass:	154.994 g/mol (anhydrous) 173.009 g/mol (monohydrate) 263.083 g/mol (hexahydrate) 281.098 g/mol (heptahydrate)
Density:	3.71 g/cm³ (anhydrous) 3.075 g/cm³ (monohydrate) 2.019 g/cm³ (hexahydrate) 1.948 g/cm³ (heptahydrate)
Crystal system:	monoclinic (heptahydrate) α=90°, γ=90° monoclinic (hexahydrate) a=10.006 Å, b=7.252 Å, c=24.122 Åα=90°, β=98.96°, γ=90°
Shapes:	Rhombic prism Deformed tetragonal bipyramid
Color:	red dark-red
Melting point:	420 °C693.15 K <br />788 °F <br />1,247.67 °R <br /> (anhydrous)
Decomposition point:	71 °C344.15 K <br />159.8 °F <br />619.47 °R <br /> (heptahydrate) 96.8 °C369.95 K <br />206.24 °F <br />665.91 °R <br /> (hexahydrate) 250 °C523.15 K <br />482 °F <br />941.67 °R <br /> (monohydrate) 735 °C1,008.15 K <br />1,355 °F <br />1,814.67 °R <br /> (anhydrous)
Refractive index:	1.639 (monohydrate) 1.540 (hexahydrate) 1.483 (heptahydrate)
Magnetic properties:	paramagnetic χ=1.00 · 10^-2cm³/mol
Stability:	erodes (heptahydrate) stable (hexahydrate) hygroscopic (anhydrous)
Toxicity:	moderately toxic LD₅₀=424mg/kg