A superacid is an acid with an acidity greater than that of 100% pure sulfuric acid. According to the modern definition, a superacid has a chemical potential of the proton higher than that of pure sulfuric acid.
Chemists use strong acids to break down other molecules. Some molecules are so strong (held together with strong chemical bonds) that they resist attack by common acids. Supercids can break down molecules that stand up to most other acids.
Commercially available superacids include trifluoromethanesulfonic acid (CF3SO3H), also known as triflic acid, and fluorosulfonic acid (FSO3H). Both acids are about a thousand times stronger (that is, have more negative H0 values) than sulfuric acid. The strongest superacids are prepared by the combination of two components, a strong Lewis acid and a strong Brønsted acid. The strongest known superacid is fluoroantimonic acid.
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References[change | change source]
- Hall NF, Conant JB (1927). "A study of superacid solutions". Journal of the American Chemical Society 49: 3062–70. doi:10.1021/ja01411a010.
- Non-simple definition: a superacid has a Hammett acidity function (H0) of −12.
- Himmel D. et al (2010). "A unified pH scale for all phases". Angew. Chem. Int. Ed. 49: 6885–6888. doi:10.1002/anie.201000252.