4Cr (s) + 3O2 (g) = Cr2O3 (s)

Find the theoretical yield in moles and grams

The balanced reaction is:

4Cr (s) + 3O2 (g) = Cr2O3 (s)

Since we are not given the amount of any of the reactants, we assume we have one gram of chromium. Calculations are as follows:

1 g Cr (1 mol Cr / 52 g Cr) (1 mol Cr2O3 / 4 mol Cr) = 0.005 mol Cr2O3

0.005 mol Cr2O3 (151.99 g Cr2O3 / 1 mol Cr2O3) = 0.7307 g Cr2O3

Therefore, the theoretical yield for 1 gram of Cr is 0.005 mol Cr2O3 or 0.7307 g Cr2O3.