Sulfur trioxide - SO3

Sulfur trioxide is an anhydride to sulfur acid and in pure form it is a fluid. Gaseous sulfur trioxide is highly irritating to the eyes, throat and respiratory tract.

It reacts with water and water vapour. Without water it’s not particularly reactive to metals.


  • Molecular weight:

    80.066 g/mol

  • Solid phase:

    Melting point: 16.9 °C

  • Liquid phase:

    Boiling point: 45 °C