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Cobalt(II)-ammonium sulfate

From Crystal growing


   Cobalt(II)-ammonium sulfate   
Names: cobalt ammonium sulfate
cobalt Tutton's salt
ammonium cobalt schoenite
ammonium cobaltous sulfate
ACoSH
ACSH
Formula: (NH4)2Co(SO4)2 (anhydrous)
(NH4)2Co(SO4)2 · 6H2O (hexahydrate)
Molar mass: 287.133 g/mol (anhydrous)
395.222 g/mol (hexahydrate)
Density: 1.897 g/cm3 (anhydrous)
Crystal system: monoclinic (hexahydrate)
a=9.2565 Å, b=12.5231 Å, c=6.2424 Åα=90°, β=107.029°, γ=90°
Shapes:
https://en.crystalls.info/w/uploads/media/7/7b/Beveled_rhombic_prism.json
https://en.crystalls.info/w/uploads/media/d/d0/Truncated_deformed_oblique_hexagonal_prism.json
https://en.crystalls.info/w/uploads/media/9/9a/Truncated_deformed_hexagonal_prism.json

Color: dark red
Decomposition point: 70 °C343.15 K <br />158 °F <br />617.67 °R <br /> (hexahydrate)
Stability: stable (hexahydrate)
hygroscopic (anhydrous)
Hardness: relatively strong
Toxicity: moderately toxic

Description

Inorganic compound, double salt of transitional metal cobalt, ammonium ion and inorganic sulfuric acid. From water solutions crystallizes as hexahydrate.

Precursors

Reaction between cobalt(II) and ammonium sulfates

Chemical equation:

(NH4)2SO4 + CoSO4 = (NH4)2Co(SO4)2


For preparation of 100.00g of cobalt(II)-ammonium sulfate hexahydrate а 66.57g of cobalt(II) sulfate hexahydrate and 33.43g of ammonium sulfate is required.

Dissolve compounds in hot water apart and then mix solutions into one container with intense stirring. Cooling or evaporation of a solution will cause double salt crystallyzation. Filter precipitate and wash it wish small amount of ethanol or acetone, then filter the solution and use it for crystal growing.

Due to the high solubility of the product, less amount of water is recommended.

Influence of impurities

Excess of one of sulfates leads to changing a shape of the final crystal. Excess of ammonium sulfate makes crystals cloudy/opaque. Small addition of zinc-ammonium sulfate or zinc-potassium sulfate changes crystal color to a lighter one, but adding a large amounts could lead to changing the crystal shape. It is also possible to cover crystals with a layer of other Tutton's salts, by placing the crystals into s saturated solution of other salt, producing a crystal-in-crystal.

Storage conditions

Store in its original form or under several layers of varnish at average humidity and room temperature. Do not store in matchboxes or cotton wool and do not heat.

Solubility

Temperatureгр/100,00 гр water
(anhydrous)(hexahydrate)
0°C273.15 K <br />32 °F <br />491.67 °R <br />~68.92
10°C283.15 K <br />50 °F <br />509.67 °R <br />~9.213.98
20°C293.15 K <br />68 °F <br />527.67 °R <br />~12.619.54
25°C298.15 K <br />77 °F <br />536.67 °R <br />~14.722.53
30°C303.15 K <br />86 °F <br />545.67 °R <br />~1725.67
40°C313.15 K <br />104 °F <br />563.67 °R <br />~21.932.46
50°C323.15 K <br />122 °F <br />581.67 °R <br />~2740.03
60°C333.15 K <br />140 °F <br />599.67 °R <br />~33.548.51
70°C343.15 K <br />158 °F <br />617.67 °R <br />~4058.09
Insoluble in ethanol and acetone.


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