Question

Two major requirements for preparation of ammonia are

• A. Low temperature and high pressure
• B. Low temperature and present pressure
• C. High temperature and low pressure
• D. High temperature and high pressure

Answer 1

Answer: (A)

This reaction is

(a) reversible,

(b) exothermic, and

(c) proceeds with a decrease in volume.

According to the Le Chatelier's principle, the favorable conditions for the formation of ammonia are,

Low temperature

The temperature should be remain as low as possible, (although at unusually low temperatures, the rate of reaction becomes slow). It has been found that the temperature, which optimizes the yield of ammonia for the reaction, is maximum at about 500°C.

High pressure

Since Haber's process proceeds with a decrease in volume, it is favored by high pressure. In actual practice, a pressure of 200 - 900 atmospheres is employed.