Dinitrogen pentoxide, N2O5, decomposes in the gas phase at room temperature according to the balanced equation
N2O5(g)→NO2(g)+NO3(g)
Calorimetric measurements carried out at 298 K indicate that the enthalpy change for the reaction is ΔH=−109kJ mol−1. No information about the activation energy is available.
Energy (kJ) is plotted on the vertical axis and reaction progress on the horizontal axis throughout this problem.
(a) Determine whether the reaction is endothermic or exothermic and cite numerical evidence from the data provided.
(b) On appropriately labeled axes, sketch a qualitative potential-energy diagram for the reaction. Your diagram must include and clearly label the following: reactants, products, transition state, and the overall enthalpy change ΔH.
(c) Explain how the magnitude of the (unknown) activation energy would influence the reaction rate, making explicit reference to features of the diagram you drew in part (b).