Toggle menu
Toggle personal menu
Not logged in
Your IP address will be publicly visible if you make any edits.

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=6.2424 Å, b=12.5231 Å, c=9.2565 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 potassium sulfate makes crystals cloudy/opaque. Small addition of zinc-potassium sulfate or magnesium-potassium sulfate changes crystal color to a lighter one. Compound could be mixed with Tutton's salts in any proportion, producing crystals with different colors and sometimes shapes. It is also possible to cover crystals with a layer of other Tutton's salt, e.g. by placing the crystal into s saturated solution of other salt, producing a crystal-in-crystal.

Influence of pH level

Addition of surfactants has a positive influence on crystal shape and transparency. For example, addition of soap containing sodium lauryl sulfate makes crystal transparent and sharp-edged. Same effect can be achieved by addition of baking soda (~1g of per 100g of solution) - a precipitate containing impurities is formed (e.g. iron salts), solution should be left intact for a while, and then filtered.

Storage conditions

Keep in its original form or under several layers of varnish at average humidity and room temperature. Do not keep crystals near heaters.

Solubility

Temperatureg/100,00 g 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.


Gallery


Video


Sources


Navigation