Failure to oxidise Fe 2+ to Fe 3+

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In summary, the conversation discusses the use of iron(II) sulfate and oxygen in the process of oxidizing copper. The standard potentials for the reactions are mentioned, but the actual results do not match the expected outcome. The speaker is seeking suggestions on how to improve the process. The suggestion of using H2O2 in HCl for etching is also mentioned.
  • #1
mooliak
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Hi all,

I have a problem which is quite basic, and I must be missing something.
Fe 3+ + e > Fe 2+ +0.77v
O2 + 4H+ + 4e > 2H2O +1.23v

Re arranged, this tells us that if we bubble air through iron 2 sulphate solution, acidified with H2SO4, the oxygen should oxidise the Fe 2+ to Fe 3+ using the protons from the sulphuric acid. Many texts also say this. However, when I put approx. 10g of green iron 2 sulphate heptahydrate into about 150ml water and add about 6 ml of c.H2SO4, and bubble air through it from a fish tank aerator, it stays green, and does not go orange as one would expect. How is this?

My project is quite simple. I want to generate Fe 3+ to dissolve metals like copper. It is a good agent to do this, but on reflection, could I not dissolve the copper directly, as the oxidation potential is easily high enough. Or would there be a rate problem?

Any suggestions would be greatly appreciated.
 
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  • #2
I would plug the concentrations into Nernst equation to see where you are - potentials you listed are standard ones, formal will be different.

As far as I know best way of oxidizing Fe2+ for etching is done with H2O2 in HCl.
 

FAQ: Failure to oxidise Fe 2+ to Fe 3+

What is the cause of failure to oxidise Fe 2+ to Fe 3+?

The most common cause of failure to oxidise Fe 2+ to Fe 3+ is the absence of a strong enough oxidizing agent. This can be due to insufficient amounts of the oxidizing agent or a lack of reaction conditions that promote oxidation.

What are the potential consequences of failure to oxidise Fe 2+ to Fe 3+?

If Fe 2+ is not oxidised to Fe 3+, it can lead to a build-up of Fe 2+ ions, which can be toxic to cells. This can also result in a decrease in the availability of Fe 3+ for important biological processes, such as oxygen transport and storage.

What methods can be used to facilitate the oxidation of Fe 2+ to Fe 3+?

There are several methods that can be used to facilitate the oxidation of Fe 2+ to Fe 3+, including the addition of a stronger oxidizing agent, increasing the temperature or pressure of the reaction, and using catalysts to speed up the reaction.

How does the pH of the solution affect the oxidation of Fe 2+ to Fe 3+?

The pH of the solution can greatly influence the oxidation of Fe 2+ to Fe 3+. In general, a lower pH (more acidic) can promote oxidation, while a higher pH (more basic) can inhibit it. This is because the presence of H+ ions can facilitate the transfer of electrons, while OH- ions can interfere with the process.

What are some common techniques for detecting the presence of Fe 2+ or Fe 3+?

Some common techniques for detecting the presence of Fe 2+ or Fe 3+ include colorimetric assays, which use color changes to indicate the presence of Fe ions, and spectroscopic methods, such as UV-Vis or NMR spectroscopy, which can detect changes in the electronic and magnetic properties of Fe ions. Other techniques, like electrochemical methods, can also be used to measure the oxidation state of Fe ions.

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