The thermite reaction , Fe2O3(s)+2Al(s)⟶2Fe(s)+Al2O3(s),ΔH∘ =−851.5kJ/mol
is one of the most exothermic reactions known. Because the heat released is sufficient to melt the iron product, the reaction is used to weld metal under the ocean. How much heat is released per mole of Al2O3produced? How does this amount of thermal energy compare with the energy released when 2 mol of protons and 2 mol of neutrons combine to form 1 mol of alpha particles?

Explanation:

1) The ΔH shows the heat of reaction of the reaction illustrated in the question and the negative sign shows the reaction is an exothermic reaction, meaning heat is released in this reaction. The amount of heat released in this reaction is 851.5 kilojoules per mole of Al₂O₃ produced.

2) The thermal energy of this reaction is however very low when compared to the energy released when 2 moles of protons and 2 moles of neutrons combine to form 1 mole of alpha particles. This is because, the reaction illustrated in the (1) above is a normal chemical reaction while the one that involves the protons and neutrons (as described in this section 2) is a nuclear reaction which involves large amount of energy. Nuclear reactions usually involve way larger amount of energy than ordinary chemical reactions.