Reactions[edit]
The most important reaction is its carbothermal reduction, which gives iron used in steel-making:
Fe2O3 + 3 CO → 2 Fe + 3 CO2
Another redox reaction is the extremely exothermic thermite reaction with aluminium.[11]
2 Al + Fe2O3 → 2 Fe + Al2O3
This process is used to weld thick metals such as rails of train tracks by using a ceramic container to funnel the molten iron in between two sections of rail. Thermite is also used in weapons and making small-scale cast-iron sculptures and tools.
Partial reduction with hydrogen at about 400 °C gives magnetite, a black magnetic material that contains both Fe(III) and Fe(II):[12]
3 Fe2O3 + H2 → 2 Fe3O4 + H2O
Iron(III) oxide is insoluble in water but dissolves readily in strong acid, e.g. hydrochloric and sulfuric acids. It also dissolves well in solutions of the chelating agents such as EDTA and oxalic acid.
Heating iron(III) oxides with other metal oxides or carbonates yields materials known as ferrates:[12]
ZnO + Fe2O3 → Zn(FeO2)2