Step 1: Understanding the Concept:
Haber's process is the primary industrial method for the large-scale production of ammonia (\( \text{NH}_3 \)) from nitrogen (\( \text{N}_2 \)) and hydrogen (\( \text{H}_2 \)).
The chemical reaction is given by: \( \text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g) \).
Step 2: Detailed Explanation:
This reaction is exothermic, reversible, and occurs at high pressure (around 200 atm) and moderate temperature (about 450-500 \(^\circ\)C).
To speed up the rate of reaction to reach equilibrium faster at these temperatures, a solid catalyst is used.
Historically and industrially, finely divided Iron (\( \text{Fe} \)) is employed as the main catalyst, often with molybdenum (\( \text{Mo} \)) or metal oxides like \( \text{K}_2\text{O} \) and \( \text{Al}_2\text{O}_3 \) as promoters to increase its efficiency.
Let us evaluate the other options:
(A) \( \text{V}_2\text{O}_5 \) (Vanadium pentoxide) is used in the Contact process for sulfuric acid production.
(C) Platinum (\( \text{Pt} \)) is used in the Ostwald process for nitric acid production.
(D) Nickel (\( \text{Ni} \)) is widely used in the hydrogenation of oils.
Step 3: Final Answer:
The catalyst used in Haber's process is finely divided Iron.