Re: Sulfur dioxide and acid rain

Jeff:
Thanks for the question and I'm sorry for taking so long to respond. The answer to your question about the formation of "dilute sulfuric acid" (acid rain) it Yes! Confused no doubt. While the mixing of S02 with water will produce sulfuric acid, the process is slow at best. As you mentioned, the presence of a catalyst (ie. UV, ozone, etc.) will improve the rate of formation. The process is a hydration progression from SO₂ -> SO₃ -> H₂SO₃ -> H₂SO₄. The "culprit" in acid rain is both H₂SO₃ and H₂S0₄ - depending on the availibility of atmospheric moisture for the reaction. For further information have a look at the EPA's Acid Rain information and the information on acid anhydrides.

Moderator's note:
See also "Smith acid rain" at Carmen Giunta's Classic Calculations from the History of Chemistry page.