Oleum is a chemical solution consisting of sulfur trioxide (SO₃) dissolved in concentrated sulfuric acid (H₂SO₄).

Oleum is produced in the contact process, where sulfur is oxidized to sulfur trioxide which is subsequently dissolved in concentrated sulfuric acid. Sulfuric acid itself is regenerated by dilution of part of the oleum.

#hydrogenleum #sulfuricacid #contactprocess  #sulfurtrioxide  #sulfur