Question

Why is aluminium used to join railway tracks or the cracked machine parts of ‘iron’? Write a balanced chemical equation for the reaction which occurs.

Hint:

Thermite reaction: Aluminium reduces iron oxide producing heat.

Answer 1

Aluminium is used in the thermite welding process because it is highly reactive and displaces iron from its oxide due to its higher affinity for oxygen. The heat generated melts the iron and joins the broken parts. Balanced chemical equation: \[ Fe_2O_3 + 2Al \longrightarrow 2Fe + Al_2O_3 + \text{Heat} \] This reaction is called the Thermite reaction. The molten iron fills the gap and solidifies to join the metal parts.