Haber Process
Contents
Key Stage 4
Meaning
The Haber Process is a process used to produce Ammonia from Nitrogen gas.
About the Haber Process
- In the Haber Process Nitrogen and Hydrogen gas are passed over an Iron catalyst at 450°C and a Pressure of 20,200,000Pa (200 times normal atmospheric pressure).
- The reaction in the Haber Process is a reversible reaction:
Hydrogen + Nitrogen ⇌ Ammonia
\( 3H_2(g) + N_2(g) ⇌ 2NH_3(g) \)
- The reaction in the Haber Process will reach a state of dynamic equilibrium with an equilibrium position which can be changed by altering the temperature or pressure of the reaction mixture.
- The yield can be improved by increasing the pressure inside the reaction vessel which favours the forward forward reaction.
- The Haber Process is essential to modern agriculture as it produces Nitrogen based fertilisers for crops. Without this the soil would run out of Nitrates and plants would not longer be able to grow.
(Higher) Iron Catalyst and the Haber Process
- The Iron catalyst increases the rate of reaction.
- However, this works for both the forward and back reaction so it does not affect the equilibrium position.
(Higher) Pressure and the Haber Process
- Using the balanced symbol equation for this reaction
\( 3H_2(g) + N_2(g) ⇌ 2NH_3(g) \)
- It can be seen that 4 Moles of reactants is needed to produce 2 Moles of products. This means a higher pressure will force the equilibrium position to favour the products over the reactants as they take up less volume.
(Higher) Temperature and the Haber Process
- The temperature affects both the rate of reaction and the equilibrium position.
- A higher temperature increases the rate of reaction because it causes the particles of reactant to collide more frequently.
- A higher temperature favours the back reaction because the forward reaction is exothermic and the back reaction is endothermic.
- To optimise the rate of reaction and the forward reaction the optimum temperature is 450°C. This temperature produces the best yield in the shortest time.
References
AQA
- Haber process, page 104, GCSE Chemistry; The Revision Guide, CGP, AQA
- Haber process, pages 119, 228-231, GCSE Chemistry; Third Edition, Oxford University Press, AQA
- Haber process, pages 266-7, GCSE Chemistry, Hodder, AQA
- Haber process, pages 301-303, GCSE Chemistry, CGP, AQA
- Haber process, pages 49, 209, 211, 215, 217, 219, 323, 344-5, 347, 349, GCSE Chemistry; Student Book, Collins, AQA
- Nitrogen, Haber process, pages 119, 228-231, GCSE Chemistry; Third Edition, Oxford University Press, AQA
Edexcel
- Haber process, page 121, GCSE Combined Science; The Revision Guide, CGP, Edexcel
- Haber process, pages 120-121, GCSE Chemistry, Pearson, Edexcel
- Haber process, pages 169, 201-203,
- Haber process, pages 59, 68, GCSE Chemistry; The Revision Guide, CGP, Edexcel