Chemistry question bank
Thermite is a mixture of one metal oxide and another metal powder. Usually aluminium is used as metal that reduces the metal oxide.
e.g. iron thermite (Fe2O3 + Al)
chromium thermite (Cr2O3 + Al)
copper thermite (CuO + Al)
Thermite reaction involves reduction of the metal oxide by metal. The metal should have lower reduction potential than the metal in oxide form. Aluminium is chosen as metal since it has strong affinity towards oxygen and its oxide, Al2O3 is a highly exothermic compound.
A common thermite contains ferric oxide and aluminium in 3:1 ratio by mass. It is used in thermite welding of broken iron parts. The reduction of ferric oxide by aluminium is highly exothermic and therefore the iron formed will be in the molten state.
Fe2O3 + 2Al --------> Al2O3 + 2Fe + heat
Thermite reaction involving aluminium is also called Goldschmidt alumino thermic reaction. Usually this reaction is triggered by burning magnesium ribbon in presence of Barium peroxide.
Thermite reaction is also used in pyrometallurgy of chromium and manganese. In this method, aluminium reduces chromium oxide to chromium.
Cr2O3 + 2Al --------> Al2O3 + 2Cr + heat
1) Why Al2O3 is a highly exothermic compound?
2) What happens when Mg ribbon is burned in air?
3) Describe Gold Schmidt alumino thermic process.
4) What is reduction potentia?Author: Aditya vardhan Vutturi