Consider the following set of reactions:

N2 + 2O2?N2O4 ,?H=?8 kJ/mol

N2 + O2?2NO ,?H=180 kJ/mol

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

overall: N2O4?2NO + O2

However, one of them must be reversed, reaction1: N2 + 2O2?N2O4

What is the enthalpy for reaction 1 reversed?

reaction 1 reversed: N2O4?N2 + 2O2

Express your answer numerically in kilojoules per mole.

What is the enthalpy for reaction 2?