Understanding REDOX: How Do Mn, Fe, and NH4 Oxidize in Water?

[Andre_212]

Hi,

In a water that contains manganese, iron and ammonium, I wondered what interaction they have with each other in terms of oxidation? I understand that they all oxidise but which element would oxidise first? Is it as simple as looking at the element and the shells to see which would lose an electron first?

Thanks

Regards,

Andre

 

[Borek]

1. Not sure what you mean by "interaction" - in general they get oxidized separately, and not because of the presence of the other ones, but because of the presence of the atmospheric oxygen.

2. Predicting which one gets oxidized first can get tricky, but in general it is just about redox potentials (probably the best approach: use Pourbaix diagrams).

 

[Dr Uma Sharma]

Hi,

In a water that contains manganese, iron and ammonium, I wondered what interaction they have with each other in terms of oxidation? I understand that they all oxidise but which element would oxidise first? Is it as simple as looking at the element and the shells to see which would lose an electron first?

Thanks

Regards,

Andre

It is actually based on reduction/oxidation potentials of these metals which also depends on their hydration enthalpy.

 

[Andre_212]

1. Not sure what you mean by "interaction" - in general they get oxidized separately, and not because of the presence of the other ones, but because of the presence of the atmospheric oxygen.

2. Predicting which one gets oxidized first can get tricky, but in general it is just about redox potentials (probably the best approach: use Pourbaix diagrams).

So is it just a matter of looking at which of these (ammonium, Fe, Mn) will lose the electron first. I have read that iron will oxidise first before Mn. Based on simple chemstry, Fe has two electrons on the outer shell and Mn has one. I would've thought the oxidation potential of Mn would be higher since it only has to lose 1 electron to form a complete outer shell. Ammonium NH4+, present in anaerobic groundwaters for examples also has one electron on the outer shell. But would this oxidise before iron?

 

[Andre_212]

It is actually based on reduction/oxidation potentials of these metals which also depends on their hydration enthalpy.

Thanks. As above what are the different REDOX potentials of each element. Also what do you mean by hydration enthalpy?

 

[jim mcnamara]

@Andre_212 It think your chemistry background is not strong enough to deal with the answers given. I think we'll just close the thread with a link to understanding REDOX, which usually something one learns in secondary school.



Thanks for asking a good question.