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Copper(II)-potassium sulfate

From Crystal growing


   Copper(II)-potassium sulfate   
Names: copper potassium sulfate
copper Tutton's salt
potassium copper schoenite
potassium cupric sulfate
KCuSH
Formula: K2Cu(SO4)2 (anhydrous)
K2Cu(SO4)2 · 6H2O (hexahydrate)
Molar mass: 333.864 g/mol (anhydrous)
441.953 g/mol (hexahydrate)
Crystal system: monoclinic (hexahydrate)
a=6.1674 Å, b=12.1302 Å, c=9.0851 Åα=90°, β=104.45°, γ=90°
Shapes:
https://en.crystalls.info/w/uploads/media/3/35/Deformed_tetragonal_bipyramid.json
https://en.crystalls.info/w/uploads/media/7/7b/Beveled_rhombic_prism.json
https://en.crystalls.info/w/uploads/media/b/bc/Rhombic_prism.json

Color: light-blue
Stability: stable (hexahydrate)

Description

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

Precursors

Reaction between copper(II) and potassium sulfates

Chemical equation:

K2SO4 + CuSO4 = K2Cu(SO4)2


For preparation of 100.00g of copper(II)-potassium sulfate hexahydrate а 56.49g of copper(II) sulfate pentahydrate and 39.43g of potassium 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.

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 chemicals producing buffer solutions makes a huge impact on crystal shape and opacity. Examples of such compounds are potassium dihydrophosphate and acetic acid.

Notes

Due to serious Jahn–Teller effect in a the hexaaquacopper(II) ion, this salt is very opaque.

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

Insoluble in ethanol and acetone.


Gallery


Sources


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