2) If yes would we gain more energy from using Nitrogen Dioxide in
stead of pure Oxygen as the oxidizer to react with Ethylene?
1) I am trying to understand enthalpy calculations. If I break Nitrogen atoms off of a molecule that is holding onto the Nitrogen atom with a single bond and then have the single Nitrogen atoms form a triple bond N2 all else being equal in the reaction will this result in an exothermic reaction?
The answer lies in your question itself. The bond energy of N2 molecule is 226 kcal/mol. If you are to break a N2 molecule to give 2 individual nitrogen atoms, you would need 226 kcal/mol and then combining these two individual nitrogen atoms to form N2 molecule would produce 226 kcal/mol. We know bond breaking involves addition energy whereas bond making involves release of energy. So tn this scenario the result is an exothermic reaction because 226 kcal/mol of energy is released in the process of bond making.
I'm not sure how to answer the second part though. Apologies.
2) If yes would we gain more energy from using Nitrogen Dioxide in stead of pure...