6 FeO (s) + O₃ (g) → 3 Fe₂O₃ (s)

This is an oxidation-reduction (redox) reaction:

FeO is a reducing agent, O₃ is an oxidizing agent.

Reactants:

• FeO – Iron(II) oxide
  • Other names: Ferrous oxide , Iron monoxide , Iron oxide ... show moreIron monooxide , Ferrous monoxide , Iron (II) oxide , C.I. 77489 show less
  • Appearance: Black crystals ; Black solid in various forms
• O₃ – Trioxygen
  • Other names: Ozone , 2λ4-trioxidiene; catena-trioxygen , Triatomic oxygen ... show moreO3 , [OO2] , O₃ show less
  • Appearance: Colourless to pale blue gas ; Colourless or bluish gas with characteristic odour ; Colorless to blue gas with a very pungent odor.

Products:

• Fe₂O₃ – Iron(III) oxide
  • Other names: Ferric oxide , Hematite , Ferric iron ... show moreRed iron oxide , Rouge , Maghemite , Colcothar , Iron sesquioxide , Rust , Ochre , Iron oxide dust and fume (as Fe) , Iron oxide red , Red oxide , Anhydrous ferric oxide , Iron (III) oxide , Diiron trioxide , Iron trioxide , Ferric sesquioxide , Iron(III) oxide [Iron oxide dust and fume (as Fe)] , Iron(III)oxide [Rouge] show less
  • Appearance: Red-brown solid ; Reddish brown-to-black crystals or powder ; Reddish-brown solid. [Note: Exposure to fume may occur during the arc-welding of iron.] ; A fine, red powder of ferric oxide. [Note: Usually used in cake form or impregnated in paper or cloth.]