Iron(II) to Iron(III) Oxidation by Oxygen

4Fe2+ + O2 + 4H+ → 4Fe3+ + 2H2O

Overview

Ferrous ions (Fe²⁺) are oxidized to ferric ions (Fe³⁺) by dissolved oxygen in acidic solution. This reaction is responsible for the yellowing of iron-containing groundwater upon exposure to air. The green Fe²⁺ solution turns yellow-brown as Fe³⁺ forms.

Participants

Role Substance Coefficient State
Reactant Oxygen O 1 (g)
Product Water H₂O 2 (l)

Everyday Example

Well water that is clear underground but turns rusty brown when left standing is undergoing this oxidation of dissolved iron(II) by air.

Industrial Importance

Iron(II)/iron(III) redox chemistry is fundamental to water treatment, geochemistry, soil science, and corrosion engineering.

Properties

Type
Redox
Reversible
No
Energy
Exothermic
ΔH
-176.0 kJ/mol

Related Reactions

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Frequently Asked Questions

What is the equation for Iron(II) to Iron(III) Oxidation by Oxygen?
The balanced equation is: 4Fe²⁺ + O₂ + 4H⁺ → 4Fe³⁺ + 2H₂O.
What type of reaction is Iron(II) to Iron(III) Oxidation by Oxygen?
Iron(II) to Iron(III) Oxidation by Oxygen is a redox reaction.
Is Iron(II) to Iron(III) Oxidation by Oxygen exothermic or endothermic?
Iron(II) to Iron(III) Oxidation by Oxygen is exothermic (releases energy). The enthalpy change (ΔH) is -176.0 kJ/mol.