I'm assuming that by "miles" you mean moles.
If O2 is the excess reactant, that means Fe is the limiting reactant. That means that the amount of product being formed depends on the amount of Fe reactant present. To calculate the moles of Fe2O3 formed, start with the given 6.4 moles of Fe and use the mole to mole ratio given by the reaction as shown below:
6.4 mol Fe x

=
3.2 mol Fe2O3
1 Cal ---------- 4.184 J
? Cal ---------- 130.0 J
130.0 x 1 / 4.184 => 31.07 Cal
hope this helps!
Answer:
Before performing chemical reactions, it is helpful to know how much product will be produced with given quantities of reactants. This is known as the theoretical yield. This is a strategy to use when calculating the theoretical yield of a chemical reaction. The same strategy can be applied to determine the amount of each reagent needed to produce a desired amount of product.
Explanation:
Reagent Examples
Reagents may be compounds or mixtures. In organic chemistry, most are small organic molecules or inorganic compounds. Examples of reagents include Grignard reagent, Tollens' reagent, Fehling's reagent, Collins reagent, and Fenton's reagent. However, a substance may be used as a reagent without having the word in its name.