Cobalt(II) nitrate

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  Cobalt(II) nitrate   
Names:
Formula: Co(NO3)2
Co(NO3)2 · 4H2O
Co(NO3)2 · 6H2O
SMILES: [N+](=O)([O-])[O-].[N+](=O)([O-])[O-].[Co+2]
Molar mass: 182.941 g/mol (anhydrous)
255.001 g/mol (tetrahydrate)
291.030 g/mol (hexahydrate)
Density: 2.49 g/cm3 (anhydrous)
1.88 g/cm3 (hexahydrate)
Crystal system: monoclinic (hexahydrate)
a=1.42 Å
1.4200 Å
0.1420 nm
, b=6.14 Å
6.1400 Å
0.6140 nm
, c=12.66 Å
12.6600 Å
1.2660 nm
α=90°
90°  
, β=112.79°
112°47′24.0″  
, γ=90°
90°  

monoclinic (dihydrate)
a=6.0194 Å
6.0194 Å
0.6019 nm
, b=8.6294 Å
8.6294 Å
0.8629 nm
, c=5.7294 Å
5.7294 Å
0.5729 nm
α=90°
90°  
, β=92.654°
92°39′14.4″  
, γ=90°
90°  

hexagonal (anhydrous)
a=10.5 Å
10.5000 Å
1.0500 nm
, b=10.5 Å
10.5000 Å
1.0500 nm
, c=12.837 Å
12.8370 Å
1.2837 nm
α=90°
90°  
, β=90°
90°  
, γ=120°
120°  

Forms:
https://media.crystalls.info/w/uploads/media/Hexagonal_flat_prism.json


https://media.crystalls.info/w/uploads/media/Hexagonal_pedion.json


https://media.crystalls.info/w/uploads/media/Irregular_hexagonal_pedion.json


Color: dark-red

bright-red

Melting point: 55°C
328.15 K
131 °F
590.67 °R
(hexahydrate)
83.5°C
356.65 K
182.3 °F
641.97 °R
(tetrahydrate)
Decomposition point: 74°C
347.15 K
165.2 °F
624.87 °R
(hexahydrate)
105°C
378.15 K
221 °F
680.67 °R
(tetrahydrate)
221°C
494.15 K
429.8 °F
889.47 °R
(anhydrous)
Electrical properties: dielectric
Magnetic properties: diamagnetic
Stability: erodes (hexahydrate)
hygroscopic (anhydrous)
Hardness: fragile
Toxicity: moderately toxic

Description

Inorganic compound, salt of transitional metal cobalt and inorganic nitric acid. From water solutions crystallizes as tetrahydrate and hexahydrate.

Synthesis

Reaction between cobalt(II) oxide, hydroxide or hydroxycarbonate and nitric acid

Chemical equation:

CoO + 2HNO3 = Co(NO3)2 + H2O
Co(OH)2 + 2HNO3 = Co(NO3)2 + 2H2O
Co2CO3(OH)2 + 4HNO3 = 2Co(NO3)2 + CO2↑ + 3H2O

For preparation 100g of cobalt(II) nitrate hexahydrate a 25.75g of cobalt(II) oxide, 31.94g of hydroxide or 36.40g of hydroxycarbonate and 66.62g of 65% 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 metal cobalt and diluted nitric acid

Chemical equation:

Co + 4HNO3 = Co(NO3)2 + 2NO2↑ + 2H2O

For preparation 100g of cobalt(II) nitrate hexahydrate a 20.25g of pure cobalt and 133.24g of 65% acid is required.

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

Reaction between cobalt(II) sulfate and calcium or lead(II) nitrate

You can use cobalt chloride instead of sulfate if you use lead salt.
Chemical equation:

CoSO4 + Ca(NO3)2 = CaSO4↓ + Co(NO3)2
CoSO4 + Pb(NO3)2 = PbSO4↓ + Co(NO3)2
CoCl2 + Pb(NO3)2 = PbCl2↓ + Co(NO3)2

For preparation 100g of cobalt(II) nitrate hexahydrate a 96.59g of cobalt(II) sulfate heptahydrate or 81.75g of cobalt(II) chloride hexahydrate and 113.81g of lead(II) nitrate, 81.14g of calcium nitrate tetrahydrate or 56.38g of anhydrous calcium nitrate is required.

Add to the flask with calcium or lead(II) nitrate small parts of cobalt compound solution and stir. The large amount of poorly soluble precipitate will form. Settle it out and filter the solution carefully.

Reaction between cobalt(II) hydroxide or hydroxycarbonate and ammonium nitrate

Chemical equation:

Co(OH)2 + 2NH4NO3 = Co(NO3)2 + 2H2O + 2NH3
Co2CO3(OH)2 + 4NH4NO3 = 2Co(NO3)2 + 3H2O + 2NH3↑ + CO2

For preparation 100g of cobalt(II) nitrate hexahydrate a 31.94g of cobalt(II) hydroxide or 36.40g of hydroxycarbonate and 55.01g of ammonium nitrate is required.

Add to the flask suspended in water cobalt compound and then add small parts of hot ammonium nitrate solution with heating and stirring. Emission of large amount of ammonia will begin. Attention, ammonia irritates eyes and lungs!

Influence of impurities

Usually does not grow as monocrystalline, a recrystallization is needed.

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

Temperatureg/100g of waterg/100g of ethylene glycolg/100g of dimethylformamide
(anhydrous)(hexahydrate)(anhydrous)(hexahydrate)
0°C
273.15 K
32 °F
491.67 °R
84.03
45.661 %
133.8
57.228 %
10°C
283.15 K
50 °F
509.67 °R
89.6
47.257 %
15°C
288.15 K
59 °F
518.67 °R
~94.3
48.533 %
20°C
293.15 K
68 °F
527.67 °R
98.93
49.731 %
400
80 %
25°C
298.15 K
77 °F
536.67 °R
102.43
50.6 %
20
16.667 %
30°C
303.15 K
86 °F
545.67 °R
111.4
52.696 %
40°C
313.15 K
104 °F
563.67 °R
125
55.556 %
50°C
323.15 K
122 °F
581.67 °R
~150
60 %
60°C
333.15 K
140 °F
599.67 °R
174
63.504 %
70°C
343.15 K
158 °F
617.67 °R
184.82
64.89 %
80°C
353.15 K
176 °F
635.67 °R
211
67.846 %
90°C
363.15 K
194 °F
653.67 °R
338.8
77.211 %
Soluble in ethanol, acetone, DMSO, ethyl acetate, dioxane, tetrahydrofuran and acetonitrile.

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