The Haber process

Question 1

What is the Haber process?

Answer 1

• The industrial production of ammonia from nitrogen and hydrogen

Question 2

What is the equation for the Haber process and what type of reaction is it?

Answer 2

• N2 + 3H2 = 2NH3 (+heat)
• The production of ammonia is a reversible reaction
• The production of ammonia (forward reaction) is exothermic

Question 3

What is the ammonia produced in the Haber process used for?

Answer 3

• Used to make nitrogen based fertilisers
• Fertilisers are used to grow all of the food that we eat

Question 4

Steps of the Haber process?

Answer 4

• H2 and N2 gases are pumped into the compresser through pipes
• Gasses are compressed to around 200 atmospheres inside the compresser
• The pressurised gases are pumped into the reaction tank. This tank contains catalytic iron beds at a temperature of 450 degrees. Some of the hyrogen and nitrogen react to form ammonia. Some H2 and N2 is left unreacted
• Gas is then passed into a cooling chamber. As ammonia has a higher boiling point than H2 and N2, it condenses into a liquid and is sperated from the unreacted H2 and N2 and stored
• Uncreacted H2 and N2 is recyled back into the process

Question 5

Where do the reactants for the Haber process come from?

Answer 5

• Nitrogen is obtained from the air (air is 78% nitrogen)
• Hydrogen is made from hydrocarbons

Question 6

Why do we use a temperature of 450 degrees in the Haber process?

Answer 6

• Because the forward reaction is exothermic, we use a fairly low temperature to achieve a higher % yield
• Although , a temperature lower than 450 would get a higher % yield but the rate of reaction would be too low. Therefore, to we don’t use anything lower than 450 to strike a balance between high % yield and fast rate of reaction
• Using a higher temperature would be more expensive

Question 7

Why do we use a pressure of 200 atmospheres in the Haber process?

Answer 7

• High pressure favours the side of lower molecules of gas
• Therfore, the higher the pressure, the greater the % yield of ammonia
• Increasing pressure also increases rate of reaction as particles will collide more often and therefore, there will be more succesfull collisions
• We don’t go higher than 200 atmospheres as it is very costly and dangerous

Question 8

Why do we use catalytic iron bed in the Haber process?

Answer 8

• Iron is a catalyst that offers an alternate reaction pathway with a lower activation energy for the H2 and N2 particles to react