Ammonia and fertilisers

• The Haber process


  1. Purified gases passed over iron catalyst at high temperature and high pressure

  2. Ammonia liquefies on cooling and is removed

  3. Remaining hydrogen and nitrogen recycled
• Reversible reaction


  Reaction where products can react to produce original reactants
• Dynamic equilibrium

  When forward and reverse reactions occur at exactly the same rate in a closed system
• The Haber process


  • Compromise in temperature and pressure to balance rate and yield
  • High pressure favours forward reaction but is dangerous
  • Low temperature favours forward reaction but gives slow rate
• Preparation of ammonium sulfate

  1. Add ammonia solution to dilute sulfuric acid

  2. Test with universal indicator to ensure neutral

  3. Evaporate to concentrate solution

  4. Cool until crystals form and dry sample
• Phosphate rock treated with acid

  • Nitric acid produces calcium nitrate
  • Sulfuric acid produces single superphosphate (SSP)
  • Phosphoric acid produces triple superphosphate (TSP)
• what are the conditions needed for the Haber process?

  High pressure of 400 atmospheres, iron catalyst, and high temperature of 450 degrees
• how do you get the reactants for the Haber process?

  Nitrogen is got through the air and hydrogen is got by using natural gases
• what are the main features in fertilisers?

  Nitrogen, phosphorus, potassium
• how are potassium chloride, potassium sulfate and phosphate rock obtained?

  Potassium chloride: Mining Potassium sulfate: Chemical synthesis Phosphate rock: Mining
• what does phosphate rock treated with nitric acid produce?

  calcium nitrate
• what does phosphate rock treated with sulfuric acid produce?

  single superphosphosphate
• what does phosphate rock treated with phosphoric acid produce?

  triple superphosphate
• what is the symbol equation for the ammonia reaction?

  NH3 + HNO3 → NH4NO3
• in the Haber process are there more moles of gas on the left or the right?

  On the left
• Is the Haber process exothermic or endothermic?

  Exothermic