Cobalt(II)-potassium sulfate

Cobalt(II)-potassium sulfate
Names:	cobalt-potassium sulfate potassium cobalt schoenite potassium cobaltous sulfate KCoSH KCSH
Formula:	K2Co(SO4)2 (anhydrous) K2Co(SO4)2 · 2H2O (dihydrate) K2Co(SO4)2 · 6H2O (hexahydrate)
Molar mass:	329.251 g/mol (anhydrous) 365.281 g/mol (dihydrate) 437.340 g/mol (hexahydrate)
Density:	2.207 g/cm3 (anhydrous)
Crystal system:	monoclinic (hexahydrate) a=6.1586 Å, b=12.2156 Å, c=9.0609 Åα=90°, β=104.839°, γ=90°
Shapes:	https://en.crystalls.info/w/uploads/media/7/7b/Beveled_rhombic_prism.json Beveled rhombic prism https://en.crystalls.info/w/uploads/media/d/d0/Truncated_deformed_oblique_hexagonal_prism.json Truncated deformed oblique hexagonal prism https://en.crystalls.info/w/uploads/media/9/9a/Truncated_deformed_hexagonal_prism.json Truncated deformed hexagonal prism
Color:	dark red
Decomposition point:	210 °C483.15 K <br />410 °F <br />869.67 °R <br /> (anhydrous)
Refractive index:	1.4865 (hexahydrate)
Optical properties:	pleochroism
Stability:	stable (hexahydrate) hygroscopic (anhydrous)
Hardness:	relatively strong
Toxicity:	moderately toxic

Description

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

Precursors

Reaction between cobalt(II) and potassium sulfates

Chemical equation:

K₂SO₄ + CoSO₄ = KCo(SO₄)₂↓

For preparation of 100.00g of cobalt(II)-potassium sulfate hexahydrate

hexahydrate

dihydrate

anhydrous

а 60.16g of cobalt(II) sulfate hexahydrate

hexahydrate

heptahydrate

monohydrate

anhydrous

and 39.84g 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.

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

TableGraph

Temperature	g/100,00 g water
	(anhydrous)	(hexahydrate)
0°C273.15 K <br />32 °F <br />491.67 °R <br />		25.5
25°C298.15 K <br />77 °F <br />536.67 °R <br />	23.29
30°C303.15 K <br />86 °F <br />545.67 °R <br />	26.59
40°C313.15 K <br />104 °F <br />563.67 °R <br />	33.75
50°C323.15 K <br />122 °F <br />581.67 °R <br />	41.77	108.4

Gallery

• 

  Cobalt(II)-potassium sulfateVKontakteVKontakte

• 

  Cobalt(II)-potassium sulfateVladimir Semikin, VKontakteVladimir SemikinVKontakte

• 

  Cobalt(II)-potassium sulfateVladimir Semikin, VKontakteVladimir SemikinVKontakte

Sources

• R.A.Kiper Properties of compounds. Handbook
• Ferdinando Bosi, Girolamo Belardi, and Paolo Ballirano, Structural features in Tutton’s salts K2(M2+(H2O)6)(SO4)2, with M2+ = Mg, Fe, Co, Ni, Cu, and Zn
• E. B. Rudneva, V. L. Manomenova, and A. E. Voloshin, The Study of KCSH Crystals Grown from Aqueous Solutions by Accelerated Technique
• I. I. Polovinko, S. V. Rykhlyk, V. B. Koman, V. M. Davydov, Pleochroism in potassium cobalt sulfate hexahydrate crystals
• N. A. Dyatlova, V. L. Manomenova, E. B. Rudneva, V. V. Grebenev, and A. E. Voloshin, Effect of Growth Conditions on the Functional Properties of K2Co(SO4 )2 ⋅ 6H2O Crystals

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Potassium compounds
Salts	Potassium bromate (KBrO3) • Potassium bromide (KBr) • Potassium chlorate (KClO3) • Potassium chloride (KCl) • Potassium chromate (K2CrO4) • Potassium dihydrophosphate (KH2PO4) • Potassium dichromate (K2Cr2O7) • Potassium iodide (KI) • Potassium hydrofluoride (KHF2) • Potassium hydrophosphate (K2HPO4) • Potassium hydrogen phthalate (KC8H6O4) • Potassium metavanadate (KVO3) • Potassium nitrate (KNO3) • Potassium sulfate (K2SO4) • Potassium thiocyanate (KNCS)
Double salts	Aluminum-potassium sulfate (KAl(SO4)2) • Antimony(III)-potassium tartrate (K2Sb2(C4H2O6)2) • Chromium(III)-potassium sulfate (KCr(SO4)2) • Cobalt(II)-potassium sulfate (K2Co(SO4)2) • Copper(II)-potassium sulfate (K2Cu(SO4)2) • Indium(III)-potassium sulfate (KIn(SO4)2) • Iron(II)-potassium sulfate (K2Fe(SO4)2) • Iron(III)-potassium sulfate (KFe(SO4)2) • Lithium-potassium sulfate (KLiSO4) • Magnesium-potassium sulfate (K2Mg(SO4)2) • Magnesium-potassium sulfate-chromate (K2CrO4 · MgSO4) • Manganese(II)-potassium sulfate (K2Mn(SO4)2) • Nickel-potassium sulfate (K2Ni(SO4)2) • Potassium-sodium tartrate (KNaC4H4O6) • Vanadium(III)-ammonium sulfate (NH4V(SO4)2) • Zinc-potassium sulfate (K2Zn(SO4)2)
Complexes	Potassium dioxalatocuprate(II) (K2[Cu(C2O4)2]) • Potassium hexanitrocobaltate(III) (K3[Co(NO2)6]) • Potassium hexachlororhodiate(III) (K3[RhCl6]) • Potassium hexacyanocobaltate(III) (K3[Co(CN)6]) • Potassium hexacyanoferrate(II) (K4[Fe(CN)6]) • Tripotassium-sodium hexacyanoferrate(II) (K3Na[Fe(CN)6]) • Potassium hexacyanoferrate(III) (K3[Fe(CN)6]) • Potassium hexacyanochromate(III) (K3[Co(CN)6]) • Potassium tetraiodobismuthate (К[BiI4]) • Potassium tetraiodomercurate(II) (K2[HgI4]) • Potassium trioxalatoaluminate (K3[Al(C2O4)3]) • Potassium trioxalatocobaltate(III) (K3[Co(C2O4)3]) Potassium trioxalatoferrate(III) (K3[Fe(C2O4)3]) • Potassium-sodium trioxalatoferrate(III) (K5Na[Fe(C2O4)3]2) • Dipotassium-sodium trioxalatoferrate(III) (K2Na[Fe(C2O4)3]) • Potassium trioxalatochromate(III) (K3[Cr(C2O4)3])