Question

Aluminothermy used for the spot welding of large iron structures is based upon the fact that :

• A. As compared to iron, aluminium has greater affinity for oxygen.
• B. As compared to aluminium, iron has greater affinity for oxygen.
• C. Reaction between aluminium and oxygen is endothermic..
• D. Reaction between iron oxide and aluminium is exothermic.

Answer 1

Answer: (A), (D)

The correct options are
A As compared to iron, aluminium has greater affinity for oxygen.
D Reaction between iron oxide and aluminium is exothermic.

Aluminothermy used for the spot welding of large iron structures is based upon two facts
(i) As compared to iron, aluminum has greater affinity for oxygen. hence, aluminum acts are reducing agent.
(ii) Reaction between iron oxide and aluminum is exothermic. High temperature is involved in the reaction.
Aluminum reduces iron oxide to iron.

$F{e}_2{O}_3+2Al\to 2Fe+A{l}_2{O}_3$