Moziah
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what have I made: Fe2O3, Fe3O4 or something else?
I bought some Fe2O3 off ebay to make some thermite but then figured 'why pay when i can make my own and learn stuff at the same time?'
I had some iron wool (38.6g weight) which i added to a beaker of water and 'stirred' occasionally. eventually, after drying I found a dark brown
powder (64g weight). The brown poweder is magnetic, and is not red like the stuff i bought, so figured it can't be the same. I then tried working
out he moles of substance (0.7 FE and 1.6 O) but that didn't help me... any idea what I made?
On you tube I saw Fe2O3 being made by electrolysing iron electrodes in brine, then filtering the sludge and drying - it was pretty quick too.
regards, Moziah
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Zinc
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If it is dark and magnetic perhaps it is Fe3O4 but I thought that it can not be made from iron in water.
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JohnWW
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It is probably a mixture of Fe2O3 and Fe3O4, or a non-stoichiometric form of Fe2O3, which would be ferromagnetic, like pure Fe3O4. Fe3O4 is the
result of "passivating" bulk Fe metal with a strong concentrated non-oxidizing acid. It also occurs naturally as magnetite, which is also the main
ferromagnetic mineral found in ironsands (along with some ilmenite, FeTiO3) derived from the weathering of basalt and similar basic igneous rocks.
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12AX7
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Then it would seem to be approximately FeO<SUB>2.28</SUB>, which is obviously wrong. 
Since you used water, it's a good bet some is in there. In fact, a composition closer to Fe(OH)3 or FeOOH is typical. If 38.6g of Fe(0) (atw = 56)
is oxidized to Fe(OH)3 (MW = 107), it would weigh 38.6 * 107 / 56 = 73.8 grams. Your product weighs less than this, which could be a sign of less
hydrated compounds or less oxidized metal (Fe3O4 or Fe buried under flakes of rust).
If you want Fe2O3, calcine the material at around 400C. You should have about 55 grams, and you can determine the amount of water that was removed.
Tim
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Moziah
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thanks for the comments - it makes sense - it's probably mixtures of FExOy.
Calcination sounds like the next step- although no idea how to remove the oxygen from my oven - i'll juts bung it in a whack up ithe temperature.
mmm - wonder what'll happen if i put the oven on pyrolytic clean for a couple of hours  somehting to try when i get home tomorrow.
btw - the al/fe(whatever i made) thermite worked
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12AX7
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A self cleaning cycle is about 400C, that would do nicely.
Tim
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Moziah
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WOW! after a couple of hours in the oven it changed colour to a lighter brown - tending towards red, it bacame more attracted to magentism and lost
12% of initial weight !
Thanks for the advice 
Moziah
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JohnWW
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| Quote: | | Originally posted by MoziahWOW! after a couple of hours in the oven it changed colour to a lighter brown - tending towards red, it bacame
more attracted to magentism and lost 12% of initial weight! |
You should now be able, from the 12% weight loss, assuming all H20 has been driven off, and the molecular weight of water (18.016) and atomic weight
of Fe (55.847) to get some idea of the composition of the original hydrous iron-oxide product.
If the dehydration was simply a matter of 2FeO(OH) -> Fe2O3 + H20, the weight loss would be 10.14%; while if it was a matter of 2Fe(OH)3 ->
Fe2O3 + H2O the weight loss would be 25.29%.
So the hydrous product could not have been a pure sample of either of these, although much closer to being a non-stoichiometric form of FeO(OH),
limonite.
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