Question

Explain why high pressure is used in the manufacture of ammonia by Haber's process. Stiite the law or principle used.

Answer 1

In Haber's process ammonia is manufactured using the reversible reaction: 

 `(N_2 + 3H_2)/(4 " moles") ⇌ (2NH_3)/(2 " moles")`

The forward reaction is accompanied by a decrease in the number of moles. On increasing pressure, then according to Le-Chatelier’s principle, the equilibrium will shift in a direction in which pressure decreases i.e., decrease in a number of moles takes place i.e., favor the formation of ammonia. Or in other words, an increase in pressure will favor the formation of ammonia. This is in accordance with Le-Chatelier’s principle, the law states ‘If a system at equilibrium is subjected to a change of concentration, temperature, and pressure, then the equilibrium shifts itself in a direction that tends towards the effect of change imposed.’