Thermite welding uses the strong reducing power of Aluminum to displace Iron from its oxide. This reaction is highly exothermic.
Fe₂O₃(s) + 2Al(s) → 2Fe(l) + Al₂O₃(s) + Heat
- Reduction: Fe₂O₃ loses oxygen to become Fe.
- Oxidation: Al gains oxygen to become Al₂O₃.
- Result: Molten iron (approx 2500°C) fills the gap between rails.