Question

The reaction of iron oxide with aluminium is used to join railway tracks or cracked machine parts. This is because:

• A. this displacement reaction is highly endothermic.
• B. this displacement reaction is highly exothermic.
• C. this combination reaction is highly endothermic.
• D. this combination reaction is highly exothermic.

Answer 1

The correct option is B this displacement reaction is highly exothermic.

The reaction of iron(III) oxide (${\text{Fe}}_2{\text{O}}_3$) with aluminium is used to join railway tracks or cracked machine parts. This reaction is known as the thermite reaction.

The reaction is as follows:

${\text{Fe}}_2{\text{O}}_3\text{(s)}+2\text{Al (s)}\to 2\text{Fe (l)}+{\text{Al}}_2{\text{O}}_3\text{(s)}+\text{Heat}$

This displacement reaction is highly exothermic. The amount of heat evolved is so large that the metal is produced in the molten state.