Calculate how much charcoal(carbon) is needed to reduce 40kg of Fe2O3

Answer 1

2Fe2O3 + 3C ==> 3CO2 + 4Fe
mols Fe2O3 = grams/molar mass

Using the coefficients in the balanced equation, convert mols Fe2O3 to mols C.

If you want C in grams, then g C = mols C x atomic mass C.