Chemistry, 12: Sulfur

• What are the uses of sulfur?

  Oil refining

  Fertiliser

  Paper and steel making

  Acid in car batteries
• How is sulfur produced?

  The contact process
• What are the sources of sulfur?

  Underground bedrock

  Volcanic deposits
• Describe the contact process:

  • Sulfur + oxygen is used to make sulfur dioxide
  • Sulfur dioxide is converted into sulfur trioxide by reacting with more oxygen (reversible)
  • Sulfur trioxide + sulfuric acid creates concentrated sulfuric acid (oleum)
  • Oleum + water creates sulfuric acid
• Why do you need to make oleum?

  Adding sulfur trioxide directly into water would be extremely exothermic and create acid mist
• What are the conditions for the contact process?

  Catalyst- vanadium oxide (V2O6)

  Temperature- 450C

  Pressure- 2atm
• The highest yield of sulfur trioxide would be made at low temperatures, which is too slow therefore 450C is used
• High pressure is not used as the yield is 98%

  Unconverted reactants are recycled
• What are the equations involved in the contact process?

  S + O2 -> SO2

  2SO2 + O2 ⇌ SO3

  H2SO4 + SO3 -> H2S2O7

  H2S2O7 + H2O -> 2H2SO4
• Oleum is highly corrosive

  It is a dehydrating agent, absorbing hydrogen and oxygen from compounds in the form of water.
• When oleum is added to glucose, carbon is formed

  The reaction is highly exothermic, and steam is produced

  A honeycomb structure of black carbon is also formed