We calculate for the amount of chromium metal in the reactant by, = 350 x (mass of Cr2/mass of Cr2O3) = 350 x (104/152) = 239.47 grams The amount of Cr metal in the product is only 213.2 grams. Thus, the percent yield. percent yield = (213.2 grams/239.47) x 100% = 89%