Chapter 5, Problem 5.36QE

When lightning strikes, the energy can force atmospheric nitrogen and oxygen to react to make NO:

${\text{N}}_{\text{2}}\left(\text{g}\right)+{\text{O}}_{\text{2}}\left(\text{g}\right)\to 2\text{NO}\left(\text{g}\right)\Delta H=+181.8\text{kJ}$

1. (a) Is this reaction endothermic or exothermic?
2. (b) What quantities of reactants and products are assumed if ΔH = +181.8 kJ?
3. (c) What is the enthalpy change when 3.50 g nitrogen is reacted with excess O₂(g)?