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Iron(II)-potassium sulfate | |
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Names: | dipotassium-iron sulfate ferrous potassium sulfate potassium iron sulfate potassium Mohr's salt potassium iron schoenite KISH KFSH KFeSH |
Formula: | K2Fe(SO4)2 (anhydrous) K2Fe(SO4)2 · 6H2O (hexahydrate) |
Molar mass: | 326.163 g/mol (anhydrous) 434.252 g/mol (hexahydrate) |
Density: | 2.169 g/cm3 (anhydrous) |
Crystal system: | monoclinic (hexahydrate) a=9.0766 Å, b=12.2646 Å, c=6.1689 Åα=90°, β=104.548°, γ=90° monoclinic (tetrahydrate) a=11.837 Å, b=9.547 Å, c=9.939 Åα=90°, β=94.88°, γ=90° triclinic (dihydrate) a=7.308 Å, b=10.816 Å, c=6.531 Åα=109.03°, β=94.88°, γ=94.53° |
Shapes: |
|
Color: | light-green pale-green |
Decomposition point: | 200 °C473.15 K <br />392 °F <br />851.67 °R <br /> (hexahydrate) |
Refractive index: | 1.497 (tetrahydrate) |
Stability: | stable (hexahydrate) hygroscopic (anhydrous) |
Hardness: | relatively strong (2 on Moh's scale) |
Toxicity: | non-toxic |
Description
Inorganic compound, double salt of transitional metal iron, aklaline metal potassium and inorganic sulfuric acid. From water solutions crystallizes as hexahydrate.
Minerals
Occurs in nature as mereiterite mineral.
Precursors
Reaction between iron(II) and potassium sulfates
Chemical equation:
100.00
g of iron(II)-potassium sulfate hexahydrate
а 64.02
g of iron(II) sulfate heptahydrate
and 40.13
g 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.
Reaction between iron(II) chloride or nitrate and potassium sulfate
Chemical equation:
100.00
g of iron(II)-potassium sulfate hexahydrate
а 45.78
g of potassium chloride tetrahydrate
or 66.31
g of iron(II) nitrate hexahydrate
and 80.26
g of sulfate is required.Add to the flask with saturated iron compound solution a potassium sulfate solution with stirring. Freezing this mixture will cause forming a large amount of crystalline precipitateof Mohr's salt. For purifying compound from unreacted compounds add large amount of cold ethanol or acetone to solution, salt will settle to the bottom in the form of fine crystals or powder. Filter precipitate and wash it with small amount of the same solvent, then filter the solution and use it for crystal growing.
Reaction between iron(II) sulfate and potassium nitrate or chloride
Chemical equation:
100.00
g of iron(II)-potassium sulfate hexahydrate
а 34.34
g of potassium chloride or 46.56
g of nitrate and 128.04
g of iron(II) sulfate heptahydrate
is required.Add to the flask with saturated iron(II) sulfate solution a potassium salt solution with stirring. Freezing this mixture will cause forming a large amount of crystalline precipitateof Mohr's salt. For purifying compound from unreacted compounds add large amount of cold ethanol or acetone to solution, salt will settle to the bottom in the form of fine crystals or powder. Filter precipitate and wash it with small amount of the same solvent, then filter the solution and use it for crystal growing.
Reaction between iron potassium alum, pure iron and sulfuric acid
Chemical equation:
100.00
g of iron(II)-potassium sulfate hexahydrate
а 132.21
g of iron potassium alum, 12.86
g of iron and 183.12
g of 37%
sulfuric acid is required.Add diluted acid to the flask, then add small parts of iron with pure metal iron compound with stirring until it will totally dissolve . For purifying compound from unreacted compounds add large amount of cold ethanol or acetone to solution, salt will settle to the bottom in the form of fine crystals or powder. Filter precipitate and wash it with small amount of the same solvent, then filter the solution and use it for crystal growing.
Influence of impurities
Excess of iron(II) sulfate influenses on crystal shape and leads to growth of polycrystalline.
Excess of potassium sulfate influenses on crystal shape and leads to transparency deterioration.
Addition of glycerol leads to flattening of crystal shape and positively influences on transparency.
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
Temperature | g/100,00 g water |
---|---|
0°C273.15 K <br />32 °F <br />491.67 °R <br /> | 27.9 |
70°C343.15 K <br />158 °F <br />617.67 °R <br /> | 82 |
100°C373.15 K <br />212 °F <br />671.67 °R <br /> | 109 |
Gallery
Sources
Iron compounds | |
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Salts |
Iron (Fe) • Iron(II) acetate (Fe(CH3COO)2) • Iron(II) chloride (FeCl2) • Iron(III) chloride (FeCl3) • Iron(II) citrate (FeHC3H5O(COO)3) • Iron(II) formate (Fe(COOH)2) • Iron(III) formate (Fe2(COOH)3) • Iron(II) nitrate (Fe(NO3)2) • Iron(II) phosphate (Fe3(PO4)2) • Iron(II) sulfate (FeSO4) • Iron(III) sulfate (Fe2(SO4)3) |
Double salts |
Iron(III)-ammonium sulfate ((NH4)Fe(SO4)2) • Iron(II)-ammonium sulfate ((NH4)2Fe(SO4)2) • Iron(II)-potassium sulfate (K2Fe(SO4)2) • Iron(II)-magnesium sulfate ((Fe,Mg)SO4) • Copper(II)-iron(II) sulfate ((Cu,Fe)SO4) |
Complexes |
Hexacyanoferrates • Nitroprussides • Pentachloroferrates • Trioxalatoferrates • Sodium ethylenediaminetetraacetate-ferrate(III) (Na[Fe((OOCCH2)2N(CH2)2N(CH2COO)2)]) |