The Haber Process

Question 1

Explain why a pressure of 200 atmospheres is used in the Haber process (4 marks)

Answer 1

200 atm is a compromise between percentage yield, rate of reaction, and cost
There are fewer molecules of product than reactant, so a higher pressure will result in a larger yield (of ammonia)
The reaction will be faster at higher pressures because the particles will have more energy and so will be more likely to collide and react
Generating high pressures is expensive, so we can’t use a very high pressure.

According to Le Chatilier’s principle, increasing pressure will favour the side of the reaction with the fewer gas molecules, to reduce the pressure - counteract the condition change
N₂ (g) + 3H₂ (g) ⇌ 2NH₃ (g)
(2 moles on the right compared with 4 moles to the left)

Question 2

What does the Haber process produce?

Answer 2

Ammonia (NH3)

Question 3

Give the formula for ammonia

Answer 3

NH3