Question

In the manufacture of ammonia by Haber’s process, the maximum yield of ammonia will obtained with the process having:
A. Low pressure and high temperature
B. Low pressure and low temperature
C. High pressure and high temperature
D. High pressure and low temperature

Answer 1

Hint: In the manufacturing of Haber’s process, the ammonia is formed by reacting nitrogen and hydrogen. In this reaction, one mole of nitrogen reacts with three mole of hydrogen to form two mole of ammonia. To increase the yield of ammonia the reaction follows Le Chatelier’s principle.

Complete step by step answer:
In the Haber process for manufacturing of ammonia, nitrogen combines with air to form ammonia. The reaction is a reversible reaction and is exothermic in nature. As it is an exothermic reaction, high temperature is required.
The reaction is shown below.
${N_2}(g) + 3{H_2}(g) \to 2N{H_3}$
In this reaction, one mole of nitrogen reacts with three mole of hydrogen to give two mole of ammonia.
Only 15% of nitrogen and hydrogen is converted to ammonia. To increase the amount of ammonia, the equilibrium mixture is shifted to the right.
According to Le Chatelier's principle, the amount of ammonia is increased by lowering the temperature and increasing the pressure in the reaction mixture.
Thus, in the manufacture of ammonia by Haber’s process, the maximum yield of ammonia will be obtained with the process having low temperature and high pressure.
Therefore, the correct option is D.

Note: According to Avagadro’s law the same amount of gases reacts under the same condition of temperature and pressure contains the same number of molecules. Therefore one mole of nitrogen and three mole of hydrogen is reacted. This is the proportion demanded by the equation.