Question

Give reasons for the catalytic activity of finely divided iron in Haber’s process.

Answer 1

1. Finely divided iron provides a large surface area for the adsorption of nitrogen and hydrogen gases.
2. Presence of vacant d-orbitals in iron allows the formation of intermediate complexes with reactant molecules.
3. Iron can exhibit variable oxidation states (variable valencies), helping in the formation of unstable reaction intermediates.
4. These intermediates provide an alternate reaction pathway with lower activation energy, increasing the reaction rate.
5. After the reaction, the intermediates decompose to release ammonia and regenerate the catalyst surface.
6. The overall effect is enhanced collision and combination of reactant molecules on the catalyst surface, leading to faster ammonia synthesis.