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Saerynide
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Fe3O4
How do you make Fe3O4?
A Google search yeilds zippo, and the board has discussed many ways to make Fe2O3, but Fe3O4 seems be all have been made by accident. Does anyone
have a sure fire way to make it? 
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The_Davster
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I think I have made Fe3O4. I was trying to make Fe2O3 but I obtained a black powder instead of a rust one. I simply placed a piece of steel wool
half submerged in water and waited several weeks. This was done a while ago so I probally have forgotten details.
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guy
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In my chemistry dictionary, it says that FeO decomposes to Fe and Fe3O4 below 570 C.
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darkflame89
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Isn't that magnetite?
Ignis ubique latet, naturam amplectitur omnem.
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Saerynide
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yeah
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sanity gone
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Try bruning dry steel wool in air and see if that results in the magnetite.
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I am a fish
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You really need to find a pottery supplier. Are you absolutely certain there are none where you live?
Fe3O4 is produced by digging it out of the ground. The reason you can't find methods of synthesising it, is probably due to the fact that there
is no need to.
1f `/0u (4|\\| |234d 7|-|15, `/0u |234||`/ |\\|33d 70 937 0u7 /\\/\\0|23.
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Cyrus
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I read some method on the internet where small pieces of steel wool were shoved into a copper pipe taped to a vacuum cleaner-reversed? Because of the
extra air flow, the steel wool will burn better. You could try burning steel wool or maybe even steel turnings
in a pure O2 atmosphere, this one is really fun, but it makes fumes.
Get the O2 any way you want, I like 2H2O2 --MnO2 --> 2H2O + O2.
Honestly, none of these methods are very practical though. You have got to find a pottery supplier in your area or online.
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sanity gone
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I don't think you need a pure O2 atmosphere. I'm pretty sure you make rust by oxidation in water, you make magneite by oxidation in air...
but I could be wrong.
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DirtyDan
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Ive seen tons of info of obtaining Fe2O3 and Fe3O4 from electralysis, tried it to the product just depends on the voltage/amperage if i remember right
although i have no specifics for you. Just get a ~10v ~5a power supply, some water (salt? or does that contaminate it?) and a nail. When i did it it
made a greenish brownish slurry, once filtered and dried it turned brown on the filter and black as a powder.
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unionised
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What do you get if you
mix FeCl3 solution with FeSO4 solution (in the right proportions);
add NaOH;
filter off the precipitated mixed Fe(III) and Fe(II) oxides/ hydroxides and
heat the stuff to drive off water?
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guy
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Nevermind. It just looked like it because the Hydrogen peroxide oxidezed the remaining Fe+2 ions to Fe+3 and it turned dark red.
[Edited on 7-7-2004 by guy]
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Theoretic
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I once took a gob of fine steel wool and put a burning match to it. Then I blew hard, and a kind of glowing "combustion" area appeared and
spread. It was like a burning area spreading on a large chunk of charcoal. You had to blow all the time, but it looked very nice, and I was left with
black stuff I'm sure is Fe3O4.
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Esplosivo
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The reaction quoted below was found in my 'collection' and I don't know from where I got it. I was going to use this reaction to
produce Fe3O4 for a chlorate cell next summer. Anyway here it is:
| Quote: |
Procedure for preparation of magnetite
Fe2+ + OH- + NO3 --> Fe3O4 + NH3 + H2O
Dissolve 6.95g of Ferrous sulfate in 100 mL of water. In another container dissolve 0.018g sodium nitrate and 3.75g potassium hydroxide in 50 mL of
water. Each solution is heated to about 75degC and the two solutions are mixed with vigorous stirring. A thick gelatinous green precipitate forms.
After being stirred at 90 to 100 degC for 10 min, the precipitate turns to a finely divided dense black substance. The mixture is cooled to room
temperature and is made acidic with a little 6M HCl. The precipitated magnetite is centrifuged or filtered on a medium or fine porosity sintered
glass filter and washed with water until the wash water gives no test for sulfate with barium chloride. The product is dried at 110 degC for 1 or 2
hours. The yield is about 1.75 g of magnetite.
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Quite a low yield but the product should be pure.
Edit: On reading unionised post again I've noticed that such a reaction could lead to the formation of Fe3O4, since Fe3O4 is actually a mixture
- FeO.Fe2O3 . Instead of NaOH as a base I would used some milder bases, such as NH3(aq). With strong bases the formation of ferrates could result in
loss in yield. Correct me if I'm wrong, this is just a guess.
[Edited on 13-9-2004 by Esplosivo]
Theory guides, experiment decides.
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guy
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I don't know for sure but you could take wo pieces of steel wool and attach to a battery and touch it together for a short time. It will glow
and burn and have Fe3O4.
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BrAiNFeVeR
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I'm very interested in this product too.
I made it by accident some time ago while producing FeSO4 by Fe + H2SO4.
It appeared to be a by-product at a certain pH / temperature, because I only got about 0.5 grams of it.
I have it in a vial with parafin oil and it's extremely fun to play with when a strong magnet is near 
It's cool to actually see the magnetic field in full 3D.
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Esplosivo
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| Quote: | Originally posted by BrAiNFeVeR
I'm very interested in this product too.
I made it by accident some time ago while producing FeSO4 by Fe + H2SO4.
It appeared to be a by-product at a certain pH / temperature, because I only got about 0.5 grams of it. |
What was the concentration of the acid you used? I cannot immagine any possible way in which Fe3O4 could have formed by such a rxn. Could it be that
your Fe was already contaminated?
Edit: Yesterday I set up a simple electrolysis setup, using an iron anode and a graphite cathode. As the electrolyte I used a solution of NaCl. The
set up was run for >24hrs using a car battery charger as a power supply. A brown-black precipitate was present which seems Fe3O4. The pic I have
taken do not show the real colour of the precipitate. I'll try testing the ppt later on. If this works out then the Fe3O4 required for a chlorate
cell can easily be produced.
[Edited on 14-9-2004 by Esplosivo]
Theory guides, experiment decides.
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guy
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How could that cell produce Fe3O4?
Wouldn't it make FeCl2 and NaOH which would react to form Fe(OH)2?
The black precipitate could be iron errosion which is both magnetic.
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Esplosivo
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Actually the NaCl soln was very dilute, just to increase the conductivity that's all. And from the amount of ppt collected it is actually
impossible to be erosion, quite a lot of ppt was formed. The solution is colourless, completely. Therefore there are no iron salts in there.
I've also 'tested' the solution by adding dilute NaOH. A cloudy soln resulted which was not thick, therefore showing only a low conc
of iron salts.
Theory guides, experiment decides.
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markgollum
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Way back, when I was experimenting with thermit, I made Fe2O3 by electrolysis of salt water with an iron anode as you describe. The ppt you describe
is Fe(OH)3 (grey 'cloudy' suspension, to black sludge, depending on concentration) and it IS formed by erosion of the Fe anode. Fe(OH)3
dehydrates easily to Fe2O3 (red) in the oven.
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Al Koholic
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Useful for H2 as well...
This method hasn't been mentioned yet unfortunately. By packing a pyrex tube full of steel wool and leading steam through the tube one can
prepare Fe3O4. Simply heat the pyrex tube with a bunsen burner while the steam is passing through to accelerate the reaction of H2O with Fe.
Hydrogen can then be passed through whatever cleaning situation you have in mind or simply vented off at a safe distance from the flame.
3Fe + 4H2O(g) + heat --> Fe3O4 + 4H2(g)
The process also works with Mg to produce MgO and H2.
Mg + H2O(g) + heat --> MgO + H2(g) just as an interesting side note.
This would be extremely simple.
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mick
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I have got to be wrong here but I will mention it having done a bit of welding and own an old car.
If you strip some old thick rusty metal down you go through all the layers of paint, iron 2 and 3 oxides. When you get to what looks like metal if you
start taping it with a welding hammer then stuff will start breaking up from the pitting in the iron and it is magnetic. I thought it was Fe3O4 which
is very stable and fairly strong, as long as not too much oxygen and water can get to it, other wise you end up with an electrolytic cell across it to
the iron underneath.
If you clean that stuff of and do not seal the iron properly it will rust faster than anything
If you have got an old iron structure that has been regularly painted there should be a layer of Fe3O4 next to the iron
mick
I clean every thing else off now but leave what I think is Fe3O4 and just put a few coats of good quality paint, from the primer up and cover the
thing in waxy stuff.
mick
I think the electrolytic cell only happens when there are lower oxidation levels of iron around.
mick
[Edited on 18-9-2004 by mick]
[Edited on 18-9-2004 by mick]
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elementcollector1
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Red-hot, finely powdered Fe, that is. Not something one can do on the hotplate.
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blogfast25
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Simplest way BY FAR:
Prepare solution of a ferric salt. Split it into two parts, one of two parts (by volume), one of one part (by volume).
To the one part, add some steel wool. The steel wool reduces the Fe(III) to Fe(II):
Fe(III) + Fe === > 2 Fe(II). Filter off the steel wool. This solution will now be green.
To it, add the two parts of Fe(III) solution. Now you have Fe(II) and Fe(III) in the right ratio.
Precipitate the Magnetite with ammonia. It's a black precipitate and definitely responds to strong magnets (Nd, e.g.)
This is how magnetite for ferrofluids is prepared, usually starting from PCB etchant solution.
[Edited on 23-11-2013 by blogfast25]
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bfesser
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Thread Pruned
23-11-2013 at 17:12 |
AJKOER
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Here is one of the lower temperature paths, to quote from Atomisty.com on Triferric tetroxide, Fe3O4 (link: http://iron.atomistry.com/triferric_tetroxide.html ):
"ferric oxide is heated to 400° C. in a current of hydrogen saturated with water vapour at 30° to 50° C. At higher temperatures products
increasingly rich in ferrous oxide are obtained."
I would avoid an excess of H2 due to the following possible reaction (temperature not specified):
Fe3O4 + 4 H2 ---> 3 Fe + 4 H2O (see http://bse.sci-lib.com/article005843.html )
Other interestingly comments from Atomistry.com include:
"According to Moissan, magnetic oxide of iron exists in two polymorphic forms, according to its method of preparation. The one form, obtained by high
temperature methods, such as the combustion of iron in oxygen, the action of steam on iron at red heat, and the calcination of ferric oxide at bright
red heat, is characterised by its insolubility in concentrated boiling nitric acid, by its high density (5 to 5.09), and by its resistance to further
oxidation when heated in air.
The second variety resembles the former in its black appearance and magnetic properties, but differs from it in density (4.86), in its solubility in
nitric acid, and in its tendency to oxidise to ferric oxide when calcined in air. It is converted into the other variety when raised to white heat in
nitrogen. As explained in the case of ferrous oxide, however, these differences may simply be due to variations in the states of aggregation of the
oxide, according to its method of preparation."
[Edited on 25-12-2013 by AJKOER]
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