Sulfuric acid: Contact process
Industrial Chemistry · Chemistry
Study notes
Why is SO₃ absorbed in H₂SO₄ (oleum) and not directly in water? Step 1: SO₃ + H₂O → H₂SO₄ is violently exothermic — mist forms, poor absorption. Step 2: SO₃ dissolves smoothly in 98% H₂SO₄ → oleum (H₂S₂O₇). Step 3: Oleum carefully diluted → H₂SO₄ of desired strength. Step 4: Indirect route tames the exotherm — oleum the middleman!