Nitrogen monoxide reacts with ozone in the atmosphere according to the elementary step
NO(g)+O3(g)⟶NO2(g)+O2(g)
Average bond energies (in kJ mol−1) are listed below.
Bond
N–O
O–O
O=O
N=O (in NO2)
Energy
625
146
498
607
The reaction proceeds through a single transition state in which the N–O bond in NO is partially broken while one O–O bond in O3 is partially formed into an N–O bond.
Use the information provided to analyze the transformation.
(a) Calculate the enthalpy change, ΔHrxn, for the reaction using the bond energies above.
(b) Draw a qualitative reaction energy diagram that is consistent with the magnitude and sign of ΔHrxn you obtained. Label reactants, products, activation energy, and ΔHrxn.
(c) Explain how the relative lengths of the upward and downward arrows in your diagram reflect the numerical values you calculated for energy absorbed and released.
(d) Ozone is known to be thermodynamically unstable relative to O2. Discuss how this fact is reflected in both your numerical calculation and your diagram.