Question

What is Thermite reaction? Write its uses.

Answer 1

Hint: We should know that thermite is an oxidation- reduction reaction involving a metal and another metal oxide first performed by Goldschmidt to avoid the use of carbon in smelting. But gradually its other utilities began to crop up.

Complete step by step answer:
The thermite reaction is actually a highly exothermic reaction between a metal and another metal oxide. It demonstrates a displacement reaction hence we can use it to determine the relative activity of the two metals. Let’s take the example of the reaction between the aluminium and the iron oxides, in which case aluminium acts as a reducing agent. This aluminium reduces the metal oxide, an iron (lll) oxide to produce ferrous and aluminium oxide.
The ‘Thermite’ mixture is stable until strong heating is applied, hence the need for an initiating reaction between the iron oxide and aluminum powder. Once underway, the reaction is highly exothermic, rapidly reaching temperatures as high as 2000 degree Celsius, well in excess of the melting point of iron.
The chemical reaction involved in this reaction can be illustrated as follows:
$$F{e}_2{O}_3+2Al\to 2Fe+A{l}_2{O}_3+heat$$
Since a huge amount of energy is released in this reaction, thermite reaction is used for the following:
Thermite welding utilizes molten metal to join the two conductors without requiring any external source of heat and current. This is mainly used in rail welding to connect railway tracks to each other.
This reaction also finds its application in metal refining as well as demolition of ammunition and arms.

Note: Sometimes the thermite reaction is initiated by the heat released from the mixture of potassium permanganate and glycerine in the laboratory demonstrations. Although it requires heat to be initiated, it becomes self sustaining after a while.