|MadSci Network: Chemistry|
The Guinness Book of Records that you were looking at may be a bit out of date? The information that I have is that the strongest known acid is a mixture of antimony pentafluoride, fluosulfonic acid, and sulfur trioxide. Even my information is not the latest. The pKa scale that we usually use for measuring acidity becomes quite meaningless for super-acids -- they are all just as strong as one another in aqueous solution, being completely dissociated. It is only when we go to other solvents that we can tell the differences between weaker strong acids like HCl and stronger strong acids like H2SO4 and HClO4 There is a number that can be associated with the strength of a super-acid, known as the Hammett acidity function. Its value is 11.0 for sulfuric acid (H2SO4) 12.6 for fluosulfonic acid (HSO3F) 15.2 for fluoantimonic acid (2 HF + SbF5 -- probably H2F(+)SbF6(-) ) more than 16 for fluosulfonic acid plus sulfur trioxide plus antimony pentafluoride. The reference is Greenwood & Earnshaw, Chemistry of the Elements, pages 57 and 664. This is a 1989 edition, so it is probably not the last word.
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