Moles of Na2O2 = 25/78=0.32 Moles of H2O = 12.1/18=0.6722 Since Na2O2 is the limiting reagent Heat released = 0.32*126 =40.32 kj Solution Moles of Na2O2 = 25/78=0.32 Moles of H2O = 12.1/18=0.6722 Since Na2O2 is the limiting reagent Heat released = 0.32*126 =40.32 kj.