Question

If 300.0 grams of FeCr2O7 react, how many grams of O2 will be consumed

Answer 1

You are given 300 grams of FeCr2O7. You are required to get the mass of O2 in grams. The first thing to do is to find a reaction between FeCr2O7 and O2. The balanced chemical reaction is 2Fe + 6Cr + 21/2O2 -> Fe2(Cr2O7)3. The molar mass of Fe2(Cr2O7)3 is 759.65 grams per mole and 32 grams per mole for O2.  

300g Fe2(Cr2O7)3 (1 mol Fe2(Cr2O7)3/759.65 g Fe2(Cr2O7)3)(21/2 mol O2/1 mole Fe2(Cr2O7)3)(32 g O2/1 mole O2) = 132.7 g O2