Which Iron Ion Is Truly More Stable, Fe2+ or Fe3+?

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Discussion Overview

The discussion revolves around the stability of iron ions, specifically comparing Fe2+ and Fe3+. Participants explore the implications of electronic structure, hydration energy, and ionization energies in different contexts, including aqueous solutions and complex formations.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants argue that Fe3+ is more stable due to its half-filled d-orbital configuration, while others point out that the standard electrode potential suggests that Fe2+ formation is favored.
  • One participant questions the context of stability, asking what state of iron is being considered when discussing electronic configurations versus reduction potentials.
  • Several participants propose that Fe2+ is more stable in aqueous solution due to its more negative hydration energy, prompting inquiries about conditions under which Fe3+ might be more stable.
  • Another participant suggests that stability should also consider ionization energies and their relation to electronic configurations, indicating that this could be explored in inorganic chemistry texts.

Areas of Agreement / Disagreement

Participants express differing views on the stability of Fe2+ versus Fe3+, with no consensus reached on which ion is truly more stable under all conditions discussed.

Contextual Notes

The discussion highlights the dependence of stability on various factors such as hydration energy, electronic configuration, and the presence of complexing agents, which remain unresolved.

Who May Find This Useful

This discussion may be of interest to students and professionals in chemistry, particularly those focused on inorganic chemistry and coordination chemistry.

chatelier
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In terms of electronic structure, Fe3+ is more stable than Fe2+ because it has a half filled d-orbital which gives extra stability.
i.e. Fe3+ : [Ar]3d5
Fe2+ : [Ar]3d6
But the standard electrode potential of the following reaction is 0.77V,
Fe3+(aq) + e- => Fe2+(aq)
which means formation of Fe2+is favored and Fe2+ should be more stable in this case.

so, actually, Fe2+ or Fe3+ is more stable?
 
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What state is the iron in when you're looking at electronic configurations? What state is the iron in when you're looking at the reduction potential?
 
Plz comment on my way of thinking:
Fe2+ is more stable than Fe3+ in aqueous solution because of the more -ve hydration energy of Fe2+
so in what situation will Fe3+ be more stable than Fe2+??
 
chatelier said:
Plz comment on my way of thinking:
Fe2+ is more stable than Fe3+ in aqueous solution because of the more -ve hydration energy of Fe2+

Okay.
so in what situation will Fe3+ be more stable than Fe2+??

You aren't restricted to aqueous solution. You aren't forbidden the use of chelating agents. You're not forbidden the formation of complexes.
 
in addition to what bystander noted, I think what you mean by "stability" is in regard to the ionization energies (1st, 2nd, 3rd). You'll need to consider the trend in ionization energies in relation to electronic configurations, the answer can be found in an inorganic text.
 

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