1. The problem statement, all variables and given/known data A mixture of 82.49g of aluminum and 117.65g of oxygen is allowed to react. Find the limiting reactant and determine the mass of the excess reactant present in the vessel when the reaction is complete. Balanced Equation is 4Al(s) + 3O2 ----> 2Al2O3 I found that Aluminum produces 1.56 mol of 2Al2O3 and Oxygen produces 2.45 mol of 2Al2O3 So, Aluminum is the limiting reactant. I do not know how to find out the grams of Oxygen from here though. I've been wondering since I could not do this on my first Chem exam.