Question

In the Haber process of synthesis of $NH_3$, which of the following statements is correct?
A) Mo acts as a catalyst and Fe as a promoter.
B) Fe acts as a catalyst and Mo as a promoter.
C) Fe acts as inhibitor and Mo as a catalyst.
D) Fe acts as promoter and Mo as autocatalyst.

Answer 1

The effects of pressure, temperature is very important in the Haber process, along with the catalyst and promoter. Catalyst increases the speed of the reaction and promoter increases the activity of the catalyst.

Complete answer:
In Haber’s process of synthesis of $NH_3$.

{N_2}(g) + 3{H_2}(g) \rightleftharpoons 2N{H_3}(g),$$$$\vartriangle H = - 92.4KJ/mol

Preparation of Ammonia goes to the process by;

At high pressure of about $200 - 250{\text{ }}atm$, and at a moderate temperature reaction takes place. Removal of ammonia is done by liquefaction. In this process, Iron is used as a catalyst and molybdenum as a promoter.
If pressure is increased then by le chatelier’s principle, the equilibrium will shift in direction of formation of Ammonia. Effects of process in this reaction is accompanied by decrease in total no. of moles.
Effects of temperature: The forward reaction is exothermic, so, if temperature is increased then according to Le Chatelier’s Principle the equilibrium shifts in backward direction.

Hence the correct answer is B).

Note: Do not confuse between options A) and B) because both look similar but there is one difference between the two. In option A) Mo acts as catalyst and Fe as a promoter which is not the correct answer.