4fe + 3o2  2fe2o3

1. classify the reaction that occurred between the iron and oxygen.

2. what evidence was there that a reaction took place?

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.