Use the data in appendix 2 to calculate the value of standard enthalpy change for the following reaction at 298K N2O4 (g) = 2NO2 (g) what is its value at 350K? State any assumptions used in your calculation. Appendix two states that the standard molar enthalpy of formation for NO2 (g) is 33.9 kJ/mol and the standard molar enthalpy of formation for N2O4 is 9.7 kJ/mol. I believe the correct answer is 58.1 kJ/mol, but I don't know the assumptions and I'm not sure if the answer would change for the different temperatures.