Sulphur and it's compounds

• Frasch process


  1. Three concentric pipes forced into Sulphur ores

  2. Superheated water at 170°C and 10atm forced down outermost pipe

  3. Hot air at 15atm forced down innermost pipe

  4. Mixture of molten Sulphur and water forced up middle pipe

  5. Sulphur solidifies at 115°C and separated from water
• The Sulphur obtained is 99% pure
• Allotropes of Sulphur

  • Rhombic Sulphur
  • Monoclinic Sulphur
• Rhombic Sulphur

  • Has an octahedral shape
  • Melts at 113°C
  • Density of 2.06g/cm³
  • Stable below 96°C
• Monoclinic Sulphur

  • Pale yellow crystalline solid
  • Hexagonal prism shape
  • Melts at 119°C
  • Density of 1.98g/cm³
  • Gradually changes to rhombic Sulphur below 96°C
• Transition temperature


  The temperature at which one allotrope of an element changes to another
• Non-crystalline forms of Sulphur

  • Colloidal Sulphur
  • Powdery Sulphur
  • Plastic Sulphur
• Plastic Sulphur

  1. Obtained by heating powdery Sulphur until it boils

  2. Boiling Sulphur poured into a thin continuous stream in a beaker of water
• Colloidal Sulphur

  Obtained by reacting Sodium thiosulphate with hydrochloric acid
• Sulphur

  • Yellow non-metallic element
  • One molecule consists of a packed ring joined by strong covalent bonds
  • Soluble in organic solvents like Benzene, Methyl Benzene and Carbon(iv)sulphide
  • Insoluble in water
• Effects of heat on Sulphur

  1. Melts at 113°C to a colourless amber liquid

  2. Liquid gradually darkens on further heating

  3. At 160°C, becomes reddish-brown and very viscous

  4. Above 160°C, liquid further darkens

  5. Near boiling point, liquid becomes more mobile due to breaking of long chains to shorter chains

  6. Liquid boils at 444°C forming reddish-brown vapour of S₂, S₆ and S₈ molecules which cool to form yellow sublimate "flowers of Sulphur"
• Sulphur(iv)oxide


  • Formed when Sulphur burns in air with a bright blue flame
  • Acidic oxides that turn moist blue litmus paper red
• Reactions of Sulphur


  1. Sulphur combines directly with elements like iron and copper to form sulphides

  2. Sulphur combines with non-metals like carbon and hydrogen to form non-metallic compounds
• Reactions of Sulphur with acids

  1. Oxidized by concentrated Nitric(v)acid and Sulphuric(vi)acid

  2. Concentrated Nitric(v)acid oxidizes Sulphur to Hydrogen sulphate, reducing to Nitrogen(iv)oxide

  3. Concentrated Sulphuric(vi)acid oxidizes Sulphur to Sulphur(iv)oxide, reducing to Sulphur(iv)oxide and water