The preparation of NO2(g) from N2(g) and O2(g) is an endothermic reaction: N2(g)+O2(g) yields NO2(g); (unbalanced) The enthalpy change of reaction for the balanced equation (with lowest whole-number coefficients) is H 67.7 kJ. If 2.50 102 mL of N2(g) at 100.C and 3.50 atm and 4.50 102 mL of O2(g) at 100.C and 3.50 atm are mixed, what amount of heat is necessary to synthesize NO2(g)?