List of the Strong Acids

Sulfuric acid bonds
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by Anne Marie Helmenstine, Ph.D.
Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.
Updated January 12, 2019

In chemistry, there are seven "strong" acids. What makes them "strong" is the fact that they completely dissociate into their ions (H+ and an anion) when they are mixed with water. Every other acid is a weak acid. Because there are only seven strong acids, it is easy to commit the list to memory. Note that some chemistry instructors may refer only to six strong acids. That typically means the first six acids on this list:

  • HCl: Hydrochloric acid
  • HNO3: Nitric acid
  • H2SO4: Sulfuric acid
  • HBr: Hydrobromic acid
  • HI: Hydroiodic acid (also known as hydriodic acid)
  • HClO4: Perchloric acid
  • HClO3: Chloric acid

As the strong acids become more concentrated, they may be unable to fully dissociate. The rule of thumb is that a strong acid is 100 percent dissociated in solutions of 1.0 M or less.