Now consider the following set of reactions:

2NO2?2NO + O2 ,?H=109 kJ/mol

N2O4?2NO + O2 ,?H=172 kJ/mol

Part A

The equations given in the problem introduction can be addedtogether to give the following reaction:

overall: N2O4?2NO2

However, one of them must be reversed. Which one?

reaction 1: 2NO2?2NO + O2

reaction 2: N2O4?2NO + O2

Part B

What is the enthalpy for reaction 1 reversed?

reaction 1 reversed: 2NO + O2?2NO2

Express your answer numerically in kilojoules per mole.

Part C

What is the enthalpy for the following reaction?

overall: N2O4?2NO2

Express your answer numerically in kilojoules per mole.