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The Haber Process

The Haber Process. It’s importance to mankind. Making AMMONIA. In 1909 Fritz Haber established the conditions to produce ammonia The Haber synthesis was developed into an industrial process by Carl Bosch. Raw materials. NITROGEN from the fractional distillation of air

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The Haber Process

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  1. The Haber Process It’s importance to mankind

  2. Making AMMONIA • In 1909 Fritz Haber established the conditions to produce ammonia • The Haber synthesis was developed into an industrial process by Carl Bosch

  3. Raw materials • NITROGEN from the fractional distillation of air • HYDROGEN from the reaction of steam with hydrocarbons

  4. Overall equation: • N2 + 3H2 <=> 2 NH3 - 92.4 kJ mol-1 • A reversible reaction • It is exothermic • At dynamic equilibrium nitrogen, hydrogen and ammonia are at constant concentration

  5. Conditions which affect the RATE of reaction • An IRON catalyst lowers activationenergy so bonds between nitrogen and hydrogen are broken more easily • A high temperature increases the energy of reactants to overcome activation energy and increase rate

  6. Effect of pressure • Increasing pressure INCREASES % yield of ammonia • Equilibrium shifts to the RIGHT • WHY?

  7. Why pressure affects the equilibrium • The equation shows: • 4 molecules of gas on the LEFT • 2 molecules of gas on the RIGHT • Increasing pressure causes the equilibrium to adjust and reduce the effect by having FEWER gas molecules so shifts to the right N2 + 3H2 2 NH3

  8. Effect of Temperature • An increase in temperature will increase rate but REDUCES % yield of ammonia • Equilibrium shifts to the left • WHY?

  9. Why temperature affects the equilibrium • The reaction is EXOTHERMIC • If the temperature increases, the equilibrium shifts to the LEFT to compensate for the extra enthalpy input • N2 + 3H2  2 NH3 - 92.4 kJ mol-1 • This means less ammonia forms

  10. Temperature 450oC the reaction rate is higher, though ammonia yield is less Use of a catalyst Pressure 200 atm Ammonia yield is high Energy costs and safety concerns are minimised Removal of ammonia Optimum conditions to give maximum efficiency

  11. Measures to keep the ammonia plant efficient • Removal of ammonia as its formed by changing the gas to liquid • Continuous operation allows unreacted nitrogen and ammonia to be recycled • Building the plant close to where ammonia is needed to reduce transport costs

  12. Uses of ammonia • Synthesis of nitric acid • Explosives • Pharmaceuticals • Cleaning agents • Fertilisers • Ammonium sulphate • Ammonium nitrate

  13. Importance of fertilisers • Today 80% ammonia is used for fertilisers • As the world population increases the need for food increases • Chemical fertilisers allow crops to grow more quickly and vigorously on the same area of land year after year

  14. Importance to mankind • In World War I the Haber process was used by German industry for making explosives • In World War II use of fertilisers prevented mass starvation

  15. Post script • Today over use of fertilisers is blamed for soil erosion and loss of agricultural land world wide • Over use of chemicals in agriculture are blamed for some medical conditions • However, the benefits of the Haber process to mankind are still of greater importance.

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