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vulture
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Potassium ferrate
This should be an even stronger oxidizer than potassium permanganate, IIRC the formula is K2FeO4. It can be produced by adding finely divided iron
powder to molten KNO3.
A violent reaction ( I assume a deflagration) should take place and the potassium ferrate can be isolated by dissolving the mess ( what else is going
to be left? ) into cold water.
Anybody ever tried this?
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Polverone
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What a coincidence! I recently tried to prepare this myself. Whatever reaction occurs certainly is not violent - or maybe I just needed finer iron
powder. With 100 mesh iron powder and KNO3 heated over a gas burner, I obtained no potassium ferrate (did not observe characteristic color on
dissolving in water) but some quantity of potassium nitrite (fumes evolved on addition of acid). I will have to try again in the future. I'll hunt
some articles on ferrates down also.
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Nils
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Jup, KNO2 is formed when KNO3 is been reduced with an easily-to-oxidize metal(Pb, Fe etc.).
Has anyone more information about K2FeO4? it sounds interesting.
What about K2BrO4?
-Nils
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Polverone
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Ferrate information now online
I have summarized and condensed a couple of journal articles on ferrate production and properties. The summary is available in the budding
sciencemadness library; http://www.sciencemadness.org and then click on "Library."
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vulture
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Nils, what do you mean with K2BrO4? Only KBrO3 exists, that is potassium bromate, a powerful oxidizer, much like KClO3.
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bonemachine
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I just want to ask if kno3 could be used in a solution electrolised with Fe electrodes to form potassium ferrate and if any dangerous fumes is given
of.
Also anyone have tested how good oxidiser it is?
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madscientist
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Electrolyzing a solution of potassium nitrate with iron electrodes will initially yield a solution of iron nitrates and potassium hydroxide, which
will soon reform potassium nitrate and precipitate iron hydroxides.
I weep at the sight of flaming acetic anhydride.
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bonemachine
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Is there any other method than melting kno3 with iron oxide to prepare ferrate? Actualy the only material close to it's synthesys i got is kno3.
thanks.
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bonemachine
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When iron nitrate decomposes in a deflagrating reaction, in what would it decompose? I mean something like FeO + N + O2 ?
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bonemachine
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Damn not a good thing that posts can not be edited. I just was curious if melting kno3 and Fe2O3 is safe (fumes giving of and stuff like that) and if
it yields pottasium ferrate. I want to try that actually but i want to be sure first. Also has anyone tested it as an oxidiser and if yes is it good
enough at low temperatures?
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bonemachine
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What color suposed to be potassium ferrate?
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Theoretic
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It's red/purple.
Could Na2FeO4 be made by electrolysing a NaOH solution with a steel or iron cathode?
The oxidizing potential of FeO4-- (converted to Fe(OH3)) is 2.20 - a stronger oxidizer than ozone!
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vulture
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IIRC, the reduction potential of ozone is -2.7V, so still more than FeO4-
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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Theoretic
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Mistake! Not 2.7, but 2.07!
Well, 2.07 according to some, 2.08 according to another, and 2.75 according to yet another source.
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vulture
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Argh. Not even mentioning the fact that it should all be negative voltages, since it's always indicated as reduction potential.
Why oh why is the world (and my psyche, but on second thought that is none of your bussiness) so confusing?
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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chemoleo
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Old topic worth reconsidering....
Well I checked... but I didnt find a detailed method on the ferrate production - via the Fe/KNO3 route. Again it's taken from
Jander&Blasius, preparative inorg. chemistry.
Here it is:
10 g of Fe powder and 20 g of KNO3 are mixed. The latter has to be molten first, then pulverised, to remove any water present.
The mixture is placed ca 1 cm thick (1/2 inch) onto an iron plate. At the edge a 1:1 mixture is added, this is needed for igniting the rest of the
mix.
Using a Bunsen burner, the 1:1 mix is ignited, and the heat is sufficient to ignite the rest of the mix. I am not quite sure why sparklers wouldnt do.
Once the reaction starts, white fumes develop, and the reaction proceeds through the whole mix (therefore it it slow, and rel. safe).
Now and here comes the important bit, potentially explaining why people before had trouble making it:
After cooling down, the product is dissolved in 50 ml ice-cold water, and filtered rapidly.
The red-violet filtrate is immediately mixed with an ice-cold BaCl2 solution. This is allowed to settle (BaFeO4 is not well soluble), and filtrated.
This is then washed with aldehyde-free EtOH/Acetone, and then dried in a desiccator.
Acidified solutions of BaFeO4 produce immediately O2, and are reduced from Fe VI to Fe III.
What I found noteworthy about this prep is that it stresses the need for ice-cold conditions, plus precipitation with barium - maybe that increases
stability of the salt, and the ease of isolation of course.
Anyway - it also means, in warm solutions, the ferrate solution (i.e, K2FeO4) is by itself not stable for a long time - possibly explaining why
it's hard to isolate this.
Apparently ferrates are stronger oxidisers than permanganates, so beware!
Although i think this is precisely what's making ferrates interesting!!!
[Edited on 19-5-2004 by chemoleo]
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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Theoretic
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"Apparently ferrates are stronger oxidisers than permanganates, so beware!"
True, they oxidize ammonia to N2 at room temperature (not the actual potential but kinetic factor I'm talking about).
Ferrates are stable in Alkaline solution, maybe dissolving them in ice cold alkali-metal hydroxide solution will stabilise the product.
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chemoleo
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Oh dear, what happened to muyos attachments? They were extremely useful  - and I
failed to save them!
Whoever has saved those ferrate pdfs, could you upload them onto the FTP please?
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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vulture
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There are quite a few PDFs about ferrates on the FTP. Atleast one about bariumferrate.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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Esplosivo
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I've got no access to the ftp. Guess I don't have books to scan lol. Well, is this the pdf you were looking for, describing the synthesis of
barium ferrate? I'm not sure this is what you attached.
Attachment: viewthread2.pdf (107kB)
This file has been downloaded 2238 times
Theory guides, experiment decides.
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Alchemist
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Ferrates
Hello all,
Just uploaded "The Ferrates" to the FTP upload file.
Have fun!
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BromicAcid
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How about instead of using iron powder as the starting material Fe2O3 is used instead. In this case it could be added directly to the molten nitrate
without the worry of deflagration mentioned in Vulture's first post. But for me it is simply a matter of convince, I've got 2 kg of Fe2O3
from my pyro days for making thermite. I think I will give this a try next weekend:
Large excess of KNO3 (with KOH added) is heated to melting point and slowly Fe2O3 is sifted in with stirring. The reaction is allowed to proceed for
several minutes at melting point then the resultant mass will be dissolved in basified ice water. The solution will be filtered then a saturated cold
BaCl2 solution will be added and any precipitate collected.
[Edited on 5/23/2004 by BromicAcid]
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BromicAcid
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I tried my above reaction outline today, but had to stop due to threat of hail and tornado's. I took a large excess of NaNO3 in prill form and
added Fe2O3 till coated, I then heated the mix in a test tube over a hotplate then after it melted and I saw the reaction was going no further I took
the massive heat to it with a propane torch. The contents began to bubble vigorusly and NO2 started to come off slightly. But I was hurried so I had
to stop here. I let the test tube cool and NaNO3 crystalized almost clear at the top whereas when hot it was a homogenous sludge. There were areas at
the bottom of the test tube that were yellow/green but that does not match the color of the ferrate anion mentioned further upthread. However when I
took the mass and added to dil. HCl a vigorous bubbling was observed. Due to time constraints this was the only test I could preform regardless of how
inconclusive it may have been.
[Tried again later, glass test tube cracked from the heat so used iron crucible, heated to bubbling for 30 minutes, dissolved mass in water, filtered,
very faintly purple/red solution, added sat. BaCl2, solution became cloudy, too little BaFeO4 to even attempt isolation so in retrospect Fe2O3 is not
the best starting material, as a matter of fact I would recomend against it.]
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Could Na2FeO4 be made by electrolysing a NaOH solution with a steel or iron cathode?
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About 3 weeks ago I tried the electrolysis of KOH using an iron pipe as my vessel. I took the KOH and packed it into the pipe and added somewhat
significant quantities of water till I had free water at the bottom. Two nickel electrodes were lowered into the solution and electrolysis commenced,
this is what it looked like after 20 minutes:
However I don't remember which is the cathode and which is the anode in the picture. However the solution to the right does have a red/purple
color that could be K2FeO4 from the KOH reacting with the vessel. I was really wondering what it could be so now I have a possibilitiy.
I guess I'll have to give this a try again except this time with iron cathode and anode doing electrolysis in a KOH paste, the reaction was fast
last time and a very distinct purple, sounds much easier then the waste of time I had with the Fe2O3/NaNO3 method that I tried eariler today.
I'll keep everyone posted.
[Edited on 5/24/2004 by BromicAcid]
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chemoleo
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Regarding your Fe2O3/NaNO3 thing, the problem may be that the reaction is simply too endothermic for Na2FeO4 to form (i.e. the oxidation potential is
not enough at the temperatures employed to oxidise the iron III+ (Fe2O3) to Fe VI+. Quite conversely, oxidation of iron to iron III + happens quite
easily, with a large reaction enthalpy. I just thought that this enthalpy is needed to further oxidise it to Fe VI+. How knows, if you heated
it up enough it would form Fe VI+ with NaNO3. But then, it would probably decompose due to the high heat....
As to electrolysis - wouldnt you just get precipitating iron hydroxide? Still it's an interesting experiment!
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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The_Davster
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I found the folowing line in "basic inorganic chemistry" by cotton and wilkenson.
"Na2O2 vigourously oxidizes some metals. For example, Fe reacts with Na2O2 violently to give FeO42-"
Thats all thats mentioned about ferrates in the entire book. Unfortunatly sodium peroxide is expensive (9$ US a ounce), but if anyone has any lying
around it would be worth a try.
BTW: Is sodium peroxide a more powerfull oxidizer than potassium ferrate?
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