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Iron(III)-ammonium sulfate | |
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Names: | ammonium-iron(III) sulfate monoammonium-iron(III) sulfate ferric-ammonium sulfate iron-ammonium alum iron alum ferric alum |
Formula: | NH4Fe(SO4)2 (anhydrous) NH4Fe(SO4)2 · 12H2O (dodecahydrate) |
Molar mass: | 266.006 g/mol (anhydrous) 482.184 g/mol (dodecahydrate) |
Density: | 1.71 g/cm3 (dodecahydrate) |
Crystal system: | monoclinic (trihydrate) a=9.982 Å, b=10.156 Å, c=9.504 Åα=90°, β=94.95°, γ=90° cubic (dodecahydrate) a=12.293 Å, b=12.293 Å, c=12.293 Åα=90°, β=90°, γ=90° |
Shapes: | |
Color: | light-violet pale-violet light-purple purple |
Melting point: | 39 °C312.15 K <br />102.2 °F <br />561.87 °R <br /> (dodecahydrate) |
Decomposition point: | 230 °C503.15 K <br />446 °F <br />905.67 °R <br /> (anhydrous) |
Refractive index: | 1.4854 (dodecahydrate) |
Stability: | erodes (dodecahydrate) hygroscopic (anhydrous) |
Hardness: | strong |
Toxicity: | slightly toxic |
Description
Inorganic compound, double salt of transitional metal iron, ammonium ion and inorganic sulfuric acid. From water solutions crystallizes as dodecahydrate.
Precursors
Reaction between pure iron, ammonium nitrate and sulfuric acid
Chemical equation:
100.00
g of iron(III)-ammonium sulfate dodecahydrate
а 11.58
g of iron, 16.60
g of ammonium nitrate and 109.95
g of 37%
sulfuric acid is required.Add acid to the flask, then add small parts of iron compound with stirring until it will totally dissolve . After reaction will stop, filter the solution and use it for crystal growing.
Reaction between iron and ammonium sulfates
Chemical equation:
100.00
g of iron(III)-ammonium sulfate dodecahydrate
а 63.88
g of iron(III) sulfate dodecahydrate
and 13.70
g 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.
Reaction between Mohr's salt and hydrogen peroxide in sulfuric acid solution
Chemical equation:
100.00
g of iron(III)-ammonium sulfate dodecahydrate
а 81.32
g of mohr's salt hexahydrate
, 11.76
g of 30%
hydrogen peroxide and 27.49
g of 37%
sulfuric acid is required.Add to the flask with sulfuric acid solution hydrogen peroxide and then add small parts of {{{reducing_agent}}} with stirring until oxide emission will stop.
Reaction between iron(III) nitrate or chloride and ammonium sulfate
Chemical equation:
100.00
g of iron(III)-ammonium sulfate dodecahydrate
а 83.78
g of iron(III) nitrate nonahydrate
or 56.06
g of iron(III) chloride hexahydrate
and 54.81
g 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, then filter the solution and use it for crystal growing.
Reaction between iron(III) sulfate and nitrate or ammonium chloride
Chemical equation:
100.00
g of iron(III)-ammonium sulfate dodecahydrate
а 85.18
g of iron(III) sulfate dodecahydrate
and 16.60
g of ammonium nitrate or 11.09
g of ammonium chloride 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, then filter the solution and use it for crystal growing.
Reaction between ammonium hydroxide, iron(III) hydroxide and sulfuric acid
Chemical equation:
100.00
g of iron(III)-ammonium sulfate dodecahydrate
а 7.27
g of ammonium hydroxide, 22.16
g of iron(III) hydroxide and 109.95
g of 37%
sulfuric acid is required.Add acid to the flask, then add small parts of ammonium and iron compound with stirring until it will totally dissolve or, if you use carbonate, until carbon dioxide emission will stop. After reaction will stop, filter the solution and use it for crystal growing.
Influence of impurities
Addition of borax has no affect on crystal shape, as it does with ammonium alum.
Notes
Unlike chrome-potassium or chrome-ammonium alums, coating with a layer of other alum (for protection against erosion) is difficult - due to high solubility, placing a iron alum crystal to solution of other alums leads to crystal dissolving.
Storage conditions
For crystal storing use hermetic vessel with small amount of saturated solution at the bottom or place wadding moistened with such solution. You can use such alternatives as vessel with vaseline or vegetable oil, organic non-hygroscopic solvent (kerosene, benzine or paraffin). Also you can use acrylate polymer or another kinds of solidifying plastic.
Solubility
Temperature | гр/100,00 гр water |
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25°C298.15 K <br />77 °F <br />536.67 °R <br /> | 124 |
100°C373.15 K <br />212 °F <br />671.67 °R <br /> | 400 |
Gallery
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Crystal of iron-ammonium alum coated with a layer of aluminum-ammoniumIron(III)-ammonium sulfate, Dmitry Shintyakov, Personal crystal growing collectionPersonal crystal growing collection
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Crystal of chromium alum, coated with a layer of ferric alumIron(III)-ammonium sulfate, Maxim Martinov, VKontakteVKontakte
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Crystal of chromium alum, coated with a layer of ferric alumIron(III)-ammonium sulfate, Maxim Martinov, VKontakteVKontakte
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Crystal of chromium alum, coated with a layer of ferric alum, near a potassium alum crystalIron(III)-ammonium sulfate, Maxim Martinov, VKontakteVKontakte
Video
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)]) |