Iron(II)-potassium sulfate
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| Iron(II)-potassium sulfate | |
|---|---|
| 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: |
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| 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.
Occurs in nature as mereiterite mineral.
Chemical equation:
100.00g of iron(II)-potassium sulfate hexahydrate а 64.02g of iron(II) sulfate heptahydrate and 40.13g 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:
100.00g of iron(II)-potassium sulfate hexahydrate а 45.78g of potassium chloride tetrahydrate or 66.31g of iron(II) nitrate hexahydrate and 80.26g of sulfate is required.Add to the flask with saturated iron compound solution a potassium sulfate solution with stirring. Cooling 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:
100.00g of iron(II)-potassium sulfate hexahydrate а 34.34g of potassium chloride or 46.56g of nitrate and 128.04g of iron(II) sulfate heptahydrate is required.Add to the flask with saturated iron(II) sulfate solution a potassium salt solution with stirring. Cooling 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:
100.00g of iron(II)-potassium sulfate hexahydrate а 132.21g of iron potassium alum, 12.86g of iron and 183.12g 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.
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.
Keep in its original form or under several layers of varnish at average humidity and room temperature. Do not keep crystals near heaters.
| 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 |
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