Given the following reactions and their enthalpy changes:
a. N2(g) + 3 H2(g) → 2 NH3(g)​​​Δ=−92.4 kJ
b. N2O(g) + 3 H2(g) → N2(g) + 3 H2O(g)​Δ=−318.3
Calculate the enthalpy change for the following reaction: ​​​2 NH3(g) + 3 O2(g) → 2 N2O(g) + 3 H2O(g)