Question

what is thermite reaction ​

Answer 1

A thermite reaction is basically iron oxide (rust) reacting with aluminum to produce molten iron. The reaction is initiated by the heat from burning magnesium ribbon which is placed in the iron oxide/aluminum mixture, this is the fuse!

Answer 2

The thermite process is a chemical reaction in which a metal oxide (preferrably molten) are displaced by another molten metal which is more reactive than the metal in the metal oxide, releasing a lot of heat. Example -

2Al + Fe2O3→ Al2O3 + 2Fe

2Al + Cr2O3 → Al2O3 + 2Cr

Here, Al (Aluminium) is more reactive than Fe (Iron) or Cr (Chromium), and displaces it from their oxides.

This reaction is used commercially to weld broken metallic parts(due to the molten metal and high temperature at which the reaction occurs). railway lines are joined in the same manner.