Question

In the reaction `Fe_2O_3 + 3CO -> 2Fe + 3CO_2`, what is the total number of moles of `CO` used to produce 112 grams of iron?

Answer 1

Find the number of moles and molar mass for 2Fe, then determine the number of moles for 3CO

Explanation:

Assume that:
n = number of moles
m = mass of substance
M = molar mass (equivalent to atomic weight in the periodic table)

`n = m -: M`

The mass (m) of Fe is found.
Your next step is to find the molar mass (M) of Fe.
The molar mass of Fe is 55.9 g/mol.

To find the number of moles for Fe:
n = 112 grams `-:` 55.9 g/mol = 2.003577818 moles of Fe(don't round because this is not your final answer or you'll get inaccurate final answer)

Note that the front number "2Fe" and "3CO" represents the number of molecules used as mole ratio. The mole ratio between Fe:CO is 2:3.

If 2 moles of iron (Fe) gives you 3 moles of carbon monoxide (CO), then 2.003577818 moles of 2Fe must give you:
[2.003577818 moles `-:` 2, then `xx` 3] = 3.0053667263 moles of CO.

You have now found the number of moles for CO.

Therefore, you now know that 3.01 moles of CO is used to produce 112 grams of Fe. (Note that 3.01 moles is rounded to 3 significant figures)