See you have to obtain moles of N2O5 to calculate moles of NO2 produced. SO moles of N2O5 = weight of N2O5 / molar mass of N2O5. Molar mass of N2O5 = 2*14+ 5*16=108 (since N=14,O=16 molar mass wise) Hence 15.2 N2O5 over 108 Solution See you have to obtain moles of N2O5 to calculate moles of NO2 produced. SO moles of N2O5 = weight of N2O5 / molar mass of N2O5. Molar mass of N2O5 = 2*14+ 5*16=108 (since N=14,O=16 molar mass wise) Hence 15.2 N2O5 over 108.