Question

Compound X and aluminium are used to join railway tracks. Name the reaction.
A. Galvanic reaction
B. Thermal reaction
C. Thermite reaction
D. Combination reaction

Answer 1

Hint: Aluminium has a unique reduction property which helps in the generation of enormous amounts of heat. This way aluminium helps in joining railway tracks. It's a reaction in which fusion of materials leads to strong bonding and acts like a welded material.

Step by step answer: The thermite reaction is a chemical reaction that takes place between a metal and a metal oxide. In thermite reaction the metal acts as a reducing agent and reduces the metal oxide to the metal. Thermite reaction leads to the production of a high amount of heat energy. So, the thermite reaction is exothermic in nature.
The thermite reaction is used for joining the railway tracks. The metal and metal oxide involved in this case are aluminium and iron (III) oxide respectively. In this reaction the aluminium metal reacts with iron (III) oxide to produce iron and aluminium oxide. This can be represented with the help of following chemical equation;
\[F{e_2}{O_3} + 2Al \to 2Fe + A{l_2}{O_3} + {\rm{ }}heat\]
In this reaction the aluminium metal acts as a reducing agent and reduces iron (III) oxide to iron and itself gets oxidised to aluminium oxide. This is because the aluminium is able to form more stable bonds with oxygen than hydrogen. A large amount of heat is evolved during the whole reaction due to which iron is produced in the molten form which is utilised in joining the railway tracks.
It can also be concluded that a thermite reaction is a redox reaction in which a more reactive metal replaces the less reactive metal from its oxide and releases a large amount of heat. Due to the exothermic nature of the thermite reaction the metal is obtained in the molten form which leads to the various uses. Thermite reaction is also used for welding purposes as well as in the metal refining and demolition of ammunition.

Hence, option (C) Thermite reaction, is the correct option.

Note: Thermite reaction is the reaction used to join the railway tracks. It is an exothermic redox reaction in which more reactive aluminium metal replaces iron from its oxide to produce molten iron which is used for joining the railway tracks. Note that it is an exothermic reaction.