Megamarko94
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Fe2O3 question?
i was trying to make some Fe2O3 by heating the iron (III) hydroxide..
And it doesnt have familiar red color:
If someone can answer why i would appreciate...
[Edited on 1-8-2011 by Megamarko94]
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blogfast25
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The colour of Fe2O3 is usually describes as 'red to brown'. That's what you've got. The exact colour depends on factors like heat and time of
calcination and granulometry of product. Yours look just fine, trust me.
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watson.fawkes
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It doesn't take a whole lot of hematite impurity to turn red to brown.
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blogfast25
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Hmmm... correct in 'theory' BUT:
I've heated crude "Fe(OH)2.nH2O" in a saucepan in open air, guestimated to about 500 C: any Fe (II) quickly oxidises to Fe(III) in air, especially
when heated strongly. I obtained a nice red (with perhaps a hint of brown) Fe2O3.
Let him heat his product somewhat higher and longer. My prediction is that it'll turn more reddish.
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Megamarko94
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i heated it to pretty high temp. it was kinda red in begining but turned brown leter.
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watson.fawkes
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If you were using an
iron crucible, I'd have to guess that the metallic Fe started to reduce your oxide a bit. At some point, high temperature will cause reduction faster
than atmospheric oxygen can reoxidize it.
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White Yeti
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I had the same problem when I tried to make some iron oxide. This is due to the fact that you've created a mixture of iron 2 and 3 oxide. Iron 2 oxide
is black and iron 3 oxide is red. Over several weeks, this powder should change into a nice red colour. If you want to speed things up, mix with some
tap water and blow air into it. I personally think it's not worth the trouble.
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blogfast25
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Quote: Originally posted by White Yeti  | | I had the same problem when I tried to make some iron oxide. This is due to the fact that you've created a mixture of iron 2 and 3 oxide. Iron 2 oxide
is black and iron 3 oxide is red. Over several weeks, this powder should change into a nice red colour. If you want to speed things up, mix with some
tap water and blow air into it. I personally think it's not worth the trouble. |
Actually, if you do have a mix of ferrous and ferric you're creating some hematite (Fe3O4). See also the preparation of ferrofluids...
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Neil
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http://en.wikipedia.org/wiki/Category:Iron_oxide_pigments
| Quote: Originally posted by blogfast25 | | The colour of Fe2O3 is usually describes as 'red to brown'. That's what you've got. The exact colour depends on factors like heat and time of
calcination and granulometry of product... |
I've prepared a bunch of samples of Fe2O3 from the same oxide sources and had numerous variations in color from tiny variations in preparation.
Grinding bright red oxide some times darkens it, sometimes grinding dark oxide brightens it. A little Mn or C contamination darkens it considerably.
Weigh a sample of iron, convert it to a hydroxide then roast it and weigh the product. when the weight matches 2Fe 3O clap and try not to think about
the color.
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