(Originais Teachy 2023) - Question Very Hard of Chemistry

When analyzing the formation reaction of ammonia (NH3) from its constituent elements, gaseous nitrogen (N2) and gaseous hydrogen (H2), it was observed that the bond enthalpy of N2 is 941 kJ/mol and that of H2 is 436 kJ/mol. Using the provided bond enthalpies and the formula that the reaction enthalpy is the bond energies of the reactants minus the bond energy of the products, calculate the enthalpy change (ΔH) for the reaction 3H2 + N2 -> 2NH3. Disregard the enthalpy changes for the H2 and N2 molecules in the gaseous form. Then, discuss qualitatively how the enthalpy change of the reaction would be affected if the reaction occurred in a closed container that already contained NH3 at the beginning of the process, assuming that the reaction was still complete, without the formation of by-products.