The synthesis of ammonia proceeds according to the balanced equation
N₂(g) + 3 H₂(g) → 2 NH₃(g)
Average bond enthalpies (kJ mol⁻¹): N≡N 945, H–H 436, N–H 391.
(a) Enumerate the bonds that must be broken and the bonds that must be formed when the reactants convert to products.
(b) Without performing a numerical calculation, use the bond enthalpy data to predict qualitatively whether the reaction is strongly exothermic, weakly exothermic, or endothermic. Justify your prediction.
(c) Despite being thermodynamically favorable, the uncatalyzed reaction proceeds extremely slowly at room temperature. Provide a detailed explanation, in terms of the transition state and bond-breaking requirements, for why the activation energy is large.
(d) Describe how the presence of an iron catalyst would change the reaction energy profile you discussed in part (c), specifying which quantities (E_a, ΔE) would and would not be affected.