The Naked Scientists

The Naked Scientists Forum

Author Topic: What are the characteristics of a solution containing ferrate(VI) ions?  (Read 6135 times)

Offline Bill.D.Katt.

  • Sr. Member
  • ****
  • Posts: 179
    • View Profile
I recently heard of the ferrate (VI) ion. I attempted a synthesis with NaClO and Fe(OH)2, and believe I attained partial success when I got a pink solution. It looked similar to a dilute MnO4 solution. Would heating this solution concentrate the FeO4 2- ions, or would it break them down?
« Last Edit: 16/06/2010 21:38:47 by chris »


 

Offline lightarrow

  • Neilep Level Member
  • ******
  • Posts: 4586
  • Thanked: 7 times
    • View Profile
I recently heard of the ferrate (VI) ion. I attempted a synthesis with NaClO and Fe(OH)2, and believe I attained partial success when I got a pink solution. It looked similar to a dilute MnO4 solution. Would heating this solution concentrate the FeO4 2- ions, or would it break them down?
Ferrate(VI) is quite unstable and lasts a few hours even at room T in solution.
 

Offline Bill.D.Katt.

  • Sr. Member
  • ****
  • Posts: 179
    • View Profile
If it only lasts a few hours wouldn't I see iron oxide or hydroxide slowly precipitating out? I've observed the solution for several days and there has been no precipitate.
 

Offline lightarrow

  • Neilep Level Member
  • ******
  • Posts: 4586
  • Thanked: 7 times
    • View Profile
I don't have idea of the FeO42- concentrations you got, maybe it was so small that you couldn't observe any precipitate (of course the fact your solution had a significant colour intensity doesn't say anything).
 

Online Bored chemist

  • Neilep Level Member
  • ******
  • Posts: 8667
  • Thanked: 42 times
    • View Profile
How sure are you that there was no Mn present?
 

Offline Bill.D.Katt.

  • Sr. Member
  • ****
  • Posts: 179
    • View Profile
I am very sure there was no Mn present. Here is what I did (I have repeated since): old BBs (with copper coating removed) + HCl +H2O2 (to speed up reaction) = FeCl2. FeCl2 +NaHCO3 (to remove potential unreacted HCl) =NaCl +CO2 +Fe(OH)2. Fe(OH)2 +NaClO. A lot of the Fe(OH)2 was unreacted so I filtered it. I added bicarb to remove potential Cl2 formation. After bicarb was added I didn't see any distinct color change, it just turned to a grey sludge. With the NaClO it immediately turned into the brown-red usually associated with iron. Also the BBs are steel, so there might be some reaction with the C that I am not aware of.
 

Offline Bill.D.Katt.

  • Sr. Member
  • ****
  • Posts: 179
    • View Profile
The solution looked like less than a gram of KMnO4 was added to 250 mls of water. Light pink.
 

Offline lightarrow

  • Neilep Level Member
  • ******
  • Posts: 4586
  • Thanked: 7 times
    • View Profile
How sure are you that there was no Mn present?
Don't know about him, but I got a pink, MnO4- - like solution too. My process was different: I molted NaOH with pure Fe2O3 (I'll write further on how much pure) and then added Na2S2O8. After have cooled the melted, I dissolved it with cold NaOH water solution and got the dark pink solution, which however got much less coloured after ~ a day, forming a brown, Fe(OH)3 - like precipitate.

Mn in the Fe2O3 can is, according to the label, less than 0.25% so it could even be that. But why the solution was darker before? No trace of black, MnO2 - like precipitate.
« Last Edit: 17/06/2010 12:56:45 by lightarrow »
 

Offline Bill.D.Katt.

  • Sr. Member
  • ****
  • Posts: 179
    • View Profile

I'm not sure, I've never been able to get it past a sharp pink color, which I got by just letting it sit and slowly evaporate. There might be a definite equilibrium in both of our solutions keeping it from reaching a higher concentration. From what I've seen in experiments the MnO4 ion is fairly stable unless you have organic molecules near it, so it shouldn't decompose in solution. I also tried the Fe +KNO3 procedure, but I can't claim any success.

The NaOH should take care of the acidic solution-decomp problems, but if it is an equilibrium then there will have to be another solution that can be concentrated because neither solutions seem to be working.
 

The Naked Scientists Forum


 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums