A chemist burns 160.0 g of Al in excess air to produce aluminum oxide, Al2O3. In the experiment she producds 260.0 g of solid aluminum oxide. The balanced chemical equation is: 4 Al + 3 O2  2 Al2O3 a. Determine the theoretical yield. b. Determine the percent yield. 4. In the reaction of Zn with HCl, 140.15 g of ZnCl2 was actually formed, although the theoretical yield was 143 g. What was the percent yield? 5. 12.5 g of copper are reacted with an excess of chlorine gas, and 25.4 g of copper(II) chloride are obtained in the experiment. Calculate the theoretical yield and the percent yield. Cu + Cl2  CuCl2