C3.5 Making ammonia

Question 1

What are the raw materials for the Haber process and where are they obtained from?

Answer 1

• Nitrogen from the air

- Hydrogen from reacting natural gas (methane) with steam

Question 2

What catalyst is used and what is the optimum temperature and pressure for the reaction?

Answer 2

An iron catalyst
450°C
200atm

Question 3

When is equilibrium reached in a reversible reaction?

Answer 3

When the reactions occur at exactly the same rate in both directions

Question 4

What do the relative amounts of all the reacting substances at equilibrium depend on?

Answer 4

The conditions of the reaction

Question 5

Does raising the temperature favour the yield from the endothermic or the exothermic side of the reaction?

Answer 5

The yield from the endothermic reaction is increased

Question 6

What happens to the yield when the temperature is decreased?

Answer 6

The yield from the exothermic reaction is increased and the endothermic yield is decreased

Question 7

Which reaction does an increase in pressure favour and what would you look at to know this?

Answer 7

• The reaction that produces the least number of molecules

- See the symbol equation

Question 8

What are four costs associated with the Haber process?

Answer 8

• Raw materials
• Equipment
• Energy
• Workers wages

Question 9

What are the 5 steps to the Haber process?

Answer 9

1) Gases obtained and pumped into compressor
2) Pressurised to about 200 atm
3) Pumped into tank w/ beds of iron catalyst at 450°C, forming ammonia
4) Unreacted N and H with ammonia into cooling tank; ammonia liquefies
5) Gases are recycled back to hot iron catalyst beds

Question 10

What are two environmental aspects of the Haber process?

Answer 10

• Higher temp= more energy= higher negative impact on environment (and cost)
• Unused reactants recycled to minimise waste (and cost of raw materials)