Advanced Topic 610 of 1102 Acids, Bases & Electrochemistry
Superacids
Acids stronger than 100 percent sulfuric acid, such as fluoroantimonic acid.
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In-depth explanation of Superacids
Superacids are acids stronger than 100 percent sulfuric acid, which is characterized by a Hammett acidity function below -12. Magic acid, a mixture of fluorosulfuric acid and antimony pentafluoride, is an example that can protonate even alkanes such as methane. Superacids are used to generate and study carbocations, which are unstable in ordinary acids. They also catalyze important industrial reactions, including the isomerization of alkanes. Their strength arises from extremely weak conjugate anions.
Going deeper: Superacids
Key ideas: Superacids are stronger than 100 percent sulfuric acid, with Hammett acidity H0 below -12 (pure H2SO4 is -12). Magic acid (HSO3F + SbF5) has H0 about -23; fluoroantimonic acid reaches about -28. They protonate hydrocarbons, forming carbocations such as tert-butyl cation that can be observed by NMR. Typically contain very weakly basic anions.
Common mistakes and connections: Mistakes: using the pH scale for them (H0 is used instead) and assuming they are the most corrosive substances per se; carborane acids are strong but gentle toward some materials. Handling needs PTFE or special containers. Applied to catalytic cracking and isomerization of alkanes. Linked to the leveling effect.
Visualization of Superacids
Superacids are stronger than 100 percent sulfuric acid (Hammett H0 -12); fluoroantimonic acid at about -28 can protonate even hydrocarbons. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Magic acid protonates methane, giving a methanium ion that cannot be formed in ordinary aqueous acids.
Frequently asked questions about Superacids
What is Superacids?
Acids stronger than 100 percent sulfuric acid, such as fluoroantimonic acid.
Is Superacids a beginner, intermediate or advanced topic?
Superacids is a advanced topic in Acids, Bases & Electrochemistry. It builds on beginner and intermediate topics, so review those first if needed.
What should I learn before Superacids?
Study these earlier topics in Acids, Bases & Electrochemistry first: Antacids, Leveling Effect, Nonaqueous Acids and Bases.
What comes after Superacids?
The next topics in Acids, Bases & Electrochemistry are Hard and Soft Acids and Bases and Acid Anhydrides.
Can I practise Superacids with quizzes?
Yes. The interactive lesson includes a self-check question on Superacids, and the Acids, Bases & Electrochemistry quiz draws on every topic in this area.
Where Superacids fits in Acids, Bases & Electrochemistry
Superacids is topic 100 of 105 in Acids, Bases & Electrochemistry.