In an industrial process the synthesis of ammonia proceeds either by an uncatalyzed pathway with an experimental activation energy of 210 kJ mol⁻¹ or by a catalyzed pathway with an activation energy of 75 kJ mol⁻¹. The overall enthalpy change of reaction is the same for both pathways.
(a) On a single set of axes draw qualitative reaction energy profiles for the uncatalyzed and catalyzed pathways. Label the reactants, products, transition states, and the forward activation energies.
(b) Explain why the presence of the catalyst allows the plant to achieve a commercially acceptable production rate at a significantly lower operating temperature than would be required for the uncatalyzed pathway.
(c) Discuss two economic or safety advantages that result from operating at the lower temperature made possible by the catalyst, linking each advantage to the concepts of activation energy and reaction rate.
(d) If the catalyst gradually deactivates so that the activation energy effectively rises toward the uncatalyzed value, predict qualitatively how the operators would need to adjust the temperature to maintain the original rate. Justify your prediction in terms of the energy distribution of molecular collisions.