Question

Which of the following catalysts is used in the Haber process for the manufacture of ammonia?
a.) Platinized asbestos
b.) Iron with a suitable promoter
c.) Copper oxide
d.) Alumina

Answer 1

Hint: To solve this question, we must know what Haber’s process is. It is performed to produce ammonia from nitrogen and oxygen at an optimum pressure and temperature.

Complete step by step solution:
We all know that catalysts speed up the rate of reaction by lowering its activation energy but without itself taking part in the reaction. A promoter is a chemical element or compound which enhances the activity of a catalyst. Sometimes the catalyst cannot speed up a reaction without the presence of a suitable promoter.
The Haber’s process combines nitrogen from the air with hydrogen derived from natural gas (methane) into ammonia. The reaction is always reversible and the production of ammonia is exothermic.
The mixture of nitrogen and hydrogen are in the ratio of 1 volume of nitrogen to 3 volumes of hydrogen as reactants.
According to Le Chatelier’s principle, a lower temperature and high pressure should favor this reaction. Hence the reaction proceeds at an optimum temperature of 400-450 degree Celsius. Finely divided Iron is used as a catalyst since it is cheap and the surface area is more. We also generally use elemental Molybdenum as a promoter in this reaction.

The reaction occurs as follows:
$$2N{H}_2+3H_2\underset{{400}^{\circ }C,250atm}{\overset{Fe,Mo}{\to }}$$$2N{H}_3$

Hence, the correct answer is Option (B) Iron with a suitable promoter.

Note: We must remember that when the catalyst is absent in this reaction, the rate is so slow that almost no reaction happens in any sensible time. The catalyst ensures that the reaction is fast enough for a dynamic equilibrium to be set up within the short period time and that the gases are actually in the reactor.