the haber process

• • the Haber process is used to make ammonia
• • the conditions of the process are:
  • 450 degrees
  • 200 atm
  • iron catalysts
• • the raw materials for the process are nitrogen and hydrogen
  • nitrogen is obtained from the air
  • hydrogen is obtained from reacting methane with steam to make hydrogen and carbon dioxide
• temperature:

  • higher temperature increases rate of reaction because particles have more kinetic energy, so more frequent successful collisions
  • higher temperature favours backwards reaction because it is exothermic, so equiibrium shifts to left, yield of ammonia reduces
  • lower temperature reduces rate of reaction
  • temperature is compromise between yielf and rate
• pressure:

  • higher pressure increases rate of reaction because particles are closer, so more frequent successful collisions
  • higher pressure favours forwards reaction because less moles made, so equilibrium shifts to right
  • higher pressure has higher possiblity of explosion, and increases cost
  • 200 atm is compromise between yield, cost and safety
• iron catalyst:

  • iron catalyst increases rate of reaction because it lowers activation energy by providing alternate pathway for reaction
  • so, rate of forwards and backwards reaction increase equally, so equilibrium position does not shift
• • an iron catalyst means a lower temperature can be used while keeping rate of reaction high
• reducing costs:

  • heat from reaction can be used to generate steam for electricity
  • recycling hydrogen and nitrogen from reaction, reduces cost of raw materials
• graph of yield vs pressure and temp:

  • at any temp, as pressure increases, yield increases
  • at any pressure, as temperature increases, yield decreases
  • as temperature increases, yield decreases