Question

What is Thermite Reaction? Explain its use and give an equation.

Answer 1

Hint: It is a reaction between an oxide of group 8 and a metal of group 13. This reaction is commonly used on railway tracks. It is a highly exothermic reaction.

Complete step by step answer:
Thermite is a composition of a metal oxide and a metal power designed to produce an effect of heat. Such substances are known to have pyrotechnic composition. They do not rely on oxygen from an external source to sustain the reaction. When thermite is ignited, it undergoes an exothermic redox reaction. The reaction is highly exothermic. Thermite mixture is basically iron oxide (\[F{e_2}{O_3}\]) reacting with Aluminium to produce molten iron. The products are aluminium oxide (\[A{l_2}{O_3}\]) and elemental iron with a large amount of heat. When the mixture is heated, it starts reacting as the aluminium is more reactive than the iron and aluminium forms stronger and stable bonds with oxygen than iron. The chemical reaction involved is:
\[F{e_2}{O_3} + Al \to A{l_2}{O_3} + Fe\]
This reaction is also known as Goldschmidt process. The reaction is a redox reaction as iron is reduced from +3 to 0, whereas aluminium is oxidised from 0 to +3.
Some uses of Thermite reaction are:
(i) The reaction is used for thermite welding, hence used to join railway tracks.
(ii) Thermites are also used in metal refining due to their extremely high temperatures.
(iii) Some thermite like mixtures are used in fire-crackers.
(iv) Thermite is also useful in making military weapons like hand grenades.

Note: Remember that a certain amount of activation energy is required to initiate this reaction, like a burning magnesium ribbon. Once started, this reaction is almost impossible to extinguish.