In the Haber process for ammonia synthesis, N2(g) + 3H2(g) ⇌ 2NH3(g), the reaction is exothermic. Which of the following conditions is used industrially to achieve a high yield while maintaining a sufficient rate?
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Correct answer
B. Moderate temperature and high pressure
Principle or equation
The Haber process uses a compromise: moderate temperature (around 450°C) to maintain rate despite exothermic equilibrium favoring low temperature, and high pressure (150-300 atm) to shift equilibrium toward fewer gas moles.
Why this answer is correct
Low temperature favors yield but slows rate; high pressure favors yield (4 moles gas to 2 moles). A catalyst (iron) is used to increase rate. Industrially, a moderate temperature (450°C) and high pressure are used.
Example
At 450°C and 200 atm with an iron catalyst, the yield of ammonia is about 15% per pass, which is economically viable.
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