Q41
General ScienceChemistry
Which is the reducing agent in the thermit reaction carried out for repairing of the railway track?
- a.Iron oxide
- b.Aluminium metal
- c.Aluminium oxide
- d.Iron metal
Answer: (B) Aluminium metal
The thermite (aluminothermic or Goldschmidt) reaction is $Fe_2O_3 + 2Al \rightarrow 2Fe + Al_2O_3 + \text{heat}$. Aluminium removes oxygen from iron(III) oxide and is itself oxidised, so aluminium metal is the reducing agent, while iron oxide is the oxidising agent. Aluminium oxide and iron are merely the products. The reaction is a highly exothermic displacement reaction, possible because aluminium lies above iron in the reactivity series; the molten iron produced is used to join rails and repair cracked machine parts. The same method is used to obtain chromium and manganese from their oxides.