Potassium trioxalatoferrate (III)
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| Potassium trioxalatoferrate(III) | |
|---|---|
| Names: | potassium ferrioxalate Potassium oxalatoferrate(III) Potassium trioxalatoferrate(III) potassium trioxalatoferriate Potassium tris(oxalato)ferrate(III) potassium tris(oxalato)ferriate |
| Formula: | K3[Fe(C2O4)3] (anhydrous) K3[Fe(C2O4)3] · 3H2O (trihydrate) |
| Molar mass: | 437.193 g/mol (anhydrous) 491.238 g/mol (trihydrate) |
| Density: | 2.13 g/cm3 (anhydrous) |
| Crystal system: | cubic (anhydrous) a=13.597 Å, b=13.597 Å, c=13.597 Åα=90°, β=90°, γ=90° monoclinic (trihydrate) a=7.762 Å, b=19.937 Å, c=10.353 Åα=90°, β=107.75°, γ=90° |
| Shapes: |
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| Color: | green |
| Decomposition point: | 230 °C503.15 K <br />446 °F <br />905.67 °R <br /> (anhydrous) 113 °C386.15 K <br />235.4 °F <br />695.07 °R <br /> (trihydrate) |
| Stability: | stable (trihydrate) |
Description
Organic coordination комплекс, salt of transitional metal iron, alkaline metal potassium and organic oxalic acid. From water solutions crystallizes as trihydrate.
Occurs in nature as minguzzite mineral.
Reaction between iron(III) chloride, potassium hydroxide or carbonate, and oxalic acid
Chemical equation:
100.00g of potassium trioxalatoferrate(III) trihydrate а 55.02g of iron(III) chloride hexahydrate, 68.53g of potassium hydroxide or 84.40g of potassium carbonate and 76.99g of oxalic acid dihydrate is required.Add to the flask with oxalic acid solution a hot iron(III) chloride solution with stirring.Add to the flask with saturated (produced on previos step) solution a potassium hydroxide or carbonate solution with stirring. Cooling this mixture will cause forming a large amount of crystalline precipitateof potassium trioxalatoferrate(III). Filter precipitate and wash it wish small amount of ethanol, then filter the solution and use it for crystal growing.
Reaction between iron(III) hydroxide or oxide, potassium hydroxide or carbonate, and oxalic acid
Chemical equation:
100.00g of potassium trioxalatoferrate(III) trihydrate а 16.25g of iron(III) oxide or 21.75g of iron(III) hydroxide, 34.26g of potassium hydroxide or 42.20g of potassium carbonate and 76.99g of oxalic acid dihydrate is required.Add acid to the flask, then add small parts of iron compound with stirring until it will totally dissolve .Add acid to the flask, then add small parts of potassium compound with stirring until heating will stop (attention, the solution may boil!) or, if you use carbonate, until carbon dioxide emission will stop. After reaction will stop, filter the solution and use it for crystal growing.
Crystalverse.com site provides a step-by-step guide about syntesis and growing big crystals of iron(III) trioxalatоferrate.
Excess of oxalic acid produces shorter crystals, and vice versa - alkaline solutions produce elongated crystals.
Notes
Direct sunlight or other sources of ultravioler radiation lead to solution changing color from green to yellow, and also lead crystals to shatter. So solution and crystals should be stored in dark place.
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 /> | 4.2 |
| 20°C293.15 K <br />68 °F <br />527.67 °R <br /> | ~16 |
| 100°C373.15 K <br />212 °F <br />671.67 °R <br /> | 105 |
Gallery
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Growth for 2 weeks, ~3.5cmPotassium trioxalatoferrate(III), Vladimir Semikin, VKontakteVKontakte
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Growth for 2 weeks, ~3.5cmPotassium trioxalatoferrate(III), Vladimir Semikin, VKontakteVKontakte
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Growth for 3 weeks, about 4.5cm x 2.6cm in sizePotassium trioxalatoferrate(III), Crystalchase21, crystalverse.comCrystalverse.com
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Growth for 3 weeksPotassium trioxalatoferrate(III), Pleasewakeupm8, reddit.comReddit.com
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Growth for 3 weeks, about 4.5cm x 2.6cm in sizePotassium trioxalatoferrate(III), Crystalchase21, crystalverse.comCrystalverse.com
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Growth for 1.5 monthPotassium trioxalatoferrate(III), Eugene Dudko, VKontakteVKontakte
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Growth for 1.5 monthPotassium trioxalatoferrate(III), Eugene Dudko, VKontakteVKontakte
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Growth for 1.5 weeksPotassium trioxalatoferrate(III), TheBASTman, reddit.comReddit.com
Video
Sources
- R.A.Kiper Properties of compounds. Handbook
- R.A.Kiper Properties of compounds. Handbook
- Personal crystal growing collection
- A. Saritha, B. Raju, M. Ramachary, P. Raghavaiah, K.A. Hussain, Synthesis, crystal structure and characterization of chiral, three-dimensional anhydrous potassium tris(oxalato)ferrate(III)
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