Question

Which of the following will favour the formation of \[N{H_3}\] by Haber’s process?
A.Increase in temperature
B.Increase in pressure
C.Addition of catalyst
D.Addition of promoter

Answer 1

Hint: The conditions for Haber’s Process are decided on the basis of Le Chatelier’s Principle. The formation of ammonia is an exothermic process. Hence an increase in temperature is not favourable. An increase in pressure and addition of catalyst will favour the reaction.

Complete Step-by-step Solution:
Ammonia is produced by Haber’s Process:
${N_2}(g) + 3{H_2}(g)\overset {iron(catalyst)} \leftrightarrows 2N{H_3}(g)$
The raw materials for the reaction are nitrogen and hydrogen gases. This is an exothermic reaction.
The conditions for the formation of ammonia by Haber’s process is based on Le Chatelier’s Principle. Let us first recall the Le Chatelier’s Principle : It says that if any system is in equilibrium and if any change is made in any of the conditions, then the system corresponds in a way to counteract the change.
We can adjust the temperature and the pressure to shift the position of the equilibrium towards the right hand side i.e. in forward direction.
Since this reaction is exothermic i.e. it liberates heat. So an increase in temperature will shift the reaction in a backward direction.
Pressure also enhances the rate of reaction. An increase in pressure will favour the above reaction in forward direction.
Use of catalysts such as an iron catalyst lowers the activation energy and increases the rate of reaction. Hence it is a favourable factor in this reaction.

Hence, the correct options are (B) and (C) .

Note: Le Chatelier’s Principle shifts the equilibrium as per the changes made in the various factors while the use of the catalyst does not shift the equilibrium. It just makes the reaction take place faster.