Strong Acids and the World's Strongest Acid

Acid melting bottle
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Most of the standardized tests students take, like the SAT and GRE, are based on your ability to reason or to understand a concept. The emphasis isn't on memorization. However, in chemistry there are some things you just have to commit to memory. You'll remember the symbols for the first few elements and their atomic masses and certain constants just from using them. On the other hand, it's harder to remember the names and structures of the amino acids and the strong acids.

The good news, regarding the strong acids, is any other acid is a weak acid. The 'strong acids' dissociate completely in water.

Strong Acids You Should Know

  • HCl - hydrochloric acid
  • HNO3 - nitric acid
  • H2SO4 - sulfuric acid
  • HBr - hydrobromic acid
  • HI - hydroiodic acid
  • HClO4 - perchloric acid

The World's Strongest Acid

Although this is the strong acid list, probably found in every chemistry text, none of these acids hold the title of World's Strongest Acid. The record-holder used to be fluorosulfuric acid (HFSO3), but the carborane superacids are hundreds of times stronger than fluorosulfuric acid and over a million times stronger than concentrated sulfuric acid. The superacids readily release protons, which is a slightly different criterion for acid strength than the ability to dissociate to release a H+ ion (a proton).

Strong Is Different from Corrosive

The carborane acids are incredible proton donors, yet they are not highly corrosive.

Corrosiveness is related to the negatively-charged part of the acid. Hydrofluoric acid (HF), for example, is so corrosve it dissolves glass. The fluoride ion attacks the silicon atom in silica glass while the proton is interacting with oxygen. Even though it is highly corrosive, hydrofluoric acid is not considered to be a strong acid because it does not completely dissociate in water.

Strength of Acids & Bases | Titration Basics