Sciencemadness Discussion Board

Iron acetate to carbonate?

RogueRose - 30-12-2017 at 02:57

I had a lot of rusty tools that I wanted to clean up so I did a vinegar soak and now have about 2L of a red/brown liquid that no longer has any vinegar smell and only a slight acidity as per pH strips. There is about 1" of precipitate on the bottom of the container which has the same color and IDK if it is rust or acetate or maybe a mixture of both.

I was going to dump the solution but thought I would see if there was anything I could try with it, either evaporating as iron (II) acetate (IDK if it is II or III actually) or maybe adding some sodium carbonate or baking soda and precipitating some iron carbonate.

From what I have read, it doesn't seem that either of these are very useful but that is only per Wiki, so I'm sure I may be missing something. If I turn it to carbonate then that could be used to make other iron salts fairly easily I would think. Would bicarbonate be strong enough for the reaction or would I need to use the carbonate?

Any suggestions on what to do and which may be more interesting of useful?

DraconicAcid - 30-12-2017 at 10:54

What you probably have is a mixture of rust and basic iron(III) acetate. I'm not sure how stable iron(II) carbonate is, but I'm pretty sure that iron(III) carbonate doesn't exist- you'll just get iron(III) (hydr)oxides and carbon dioxide.

If I wanted to separate iron from any chromium, nickel, or other metals on the tools, I'd probably add ammonia to precipitate it as the hydroxide (leaving most other transition metals in solution), and then add whichever acid I wanted to make a crystallizable iron compound.

RogueRose - 30-12-2017 at 11:38

Quote: Originally posted by DraconicAcid  
What you probably have is a mixture of rust and basic iron(III) acetate. I'm not sure how stable iron(II) carbonate is, but I'm pretty sure that iron(III) carbonate doesn't exist- you'll just get iron(III) (hydr)oxides and carbon dioxide.

Thanks for the suggestions!.


If I wanted to separate iron from any chromium, nickel, or other metals on the tools, I'd probably add ammonia to precipitate it as the hydroxide (leaving most other transition metals in solution), and then add whichever acid I wanted to make a crystallizable iron compound.


I tried a little bit of bicarbonate into the red/brown solution and I have a green/grey precipitate on the bottom and teh solution remaining has a green/brown/red tint - very faint and looks like a carbonate mix, though the carbonate has settled to the bottom nicely. The precipitate does have a slight brown "dust" on the top of the carbonate precipitate and I think it is some rust or hydroxide that doesn't convert with the bicarb.

When adding the bicarb, the clear solution starts to flocculate nicely and all the carbonate (iron) stick together and fall to the bottom which makes this a nice process IMO.

I decided not to keep the iron acetate b/c it is a real mess and stains hands (and other stuff) so I wanted to get rid of it and I can use the carbonate at a later date.

Fantasma4500 - 9-1-2018 at 12:25

i think what you have is a dirty mix of iron oxides, which breaks down into fairly pure Fe2O3 upon strong heating, any basic iron oxides would tend to react forming iron acetate
iron acetate has a brownish burgundy colour, if you must precipitate iron a fairly safe way is through iron oxalate which first up has a neat yellow colour but secondly likely can be used for making sodium nitrate by decompositing together with molten sodium nitrate, immediately forming nano iron powder that then readily absorbs sorrounding oxygen - or well thats how iron oxalate used to work.

RogueRose - 9-1-2018 at 13:17

Quote: Originally posted by Antiswat  
i think what you have is a dirty mix of iron oxides, which breaks down into fairly pure Fe2O3 upon strong heating, any basic iron oxides would tend to react forming iron acetate
iron acetate has a brownish burgundy colour, if you must precipitate iron a fairly safe way is through iron oxalate which first up has a neat yellow colour but secondly likely can be used for making sodium nitrate by decompositing together with molten sodium nitrate, immediately forming nano iron powder that then readily absorbs sorrounding oxygen - or well thats how iron oxalate used to work.


Thanks for the reply! I dried the precipitate after washing it many times to remove any sodium carbonate left behind. By the time I was finished letting it settle I had 3 distinct layers, mild green at the bottom 1/2 dark green on the top 1/2 and a very thin rust colored layer at the top.

After heating it was all a nice rust color and very, very fine powder.

Thanks for the suggestion on the oxalic acid, it does seem to work well as a rust remover but it does often leave a coating on any metal left in the water (not a big problem if only converting a solution though).