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Anne Marie Helmenstine, Ph.D.

Strong Acids and the World's Strongest Acid

By February 9, 2007

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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
Photo: Johannes Raitio , stock.xchng


February 17, 2007 at 10:14 am
(1) zaki says:

Thanks for the informative explanation about acid strength etc…very interesting…like it….

July 29, 2011 at 2:01 am
(2) shakoor says:

this xplination and info. Is very helpful 4 me.0..

October 3, 2008 at 9:04 am
(3) prerit jain says:


October 9, 2008 at 3:28 pm
(4) Someone who likes acids says:

this website is informative… ITS BRILLIANT!!!
I think you should make more things like this explaining different things…

February 7, 2009 at 7:32 am
(5) Ferjad says:

it is helpful but you should also display the pH value

February 11, 2009 at 10:58 am
(6) Nazeer says:

I had 2 do a report and almost failed but was saved by ur info thank u vry much

April 15, 2010 at 7:34 pm
(7) me says:

BTW from wikipedia it says that:
fluoroantimonic acid is 20 quintillion (2*10^19) times stronger than sulfuric acid.

May 13, 2010 at 8:38 am
(8) Mark says:

Actaully the strongest acid is Alien blood.

July 25, 2010 at 9:56 pm
(9) Matty says:

@ 4 Ferjad – For superacids, the pH scale becomes null and void – and it’s not possible for them to have an actual pH value, as pH is how an acid dissociates in water.

Superacids protonate pretty much anything, and so other acidity scales are required.

November 21, 2010 at 2:36 pm
(10) Rakesh says:

Hey guys actually Fluoroantimonic acid is the strongest acid

Fluoroantimonic acid (1990) (H0 Value = −31.3)

Carborane superacid (1969) (H0 Value = −18.0)

November 23, 2010 at 11:47 am
(11) joe says:

nice job at this

June 19, 2011 at 4:02 pm
(12) quimicalobo says:

this acid is very strong.. but the book “Acids and Bases in Organic Chemistry- Paulo Costa, Vitor Ferreira, Pierre Esteves, Mário Vasconcellos” says:
HF-SbF5 (10%mol SbF5) have Hammet scale: ~(-22)
HSO3F have Hammet scale: (-15,1)

July 28, 2011 at 9:17 pm
(13) Micah says:

Thank you! I’ve been wondering if how corrosive an acid is was related to its strength. HF(aq) was really throwing me off as being a weak acid!

September 17, 2011 at 4:23 pm
(14) adebanjo michael says:

thanks 4 d information it will really help me in school,i will pass dis across to 2 others

September 28, 2011 at 7:35 pm
(15) Simon Boateng says:

Oh i really to build up my studies and also help me to know more about acids.

October 13, 2011 at 3:20 am
(16) Anon e mous says:

nice, so corborane superacids are the strongest, but if I wanna kill someone I gotta find me sum hydrofluoric acid, thanks

October 15, 2011 at 8:21 am
(17) Chemistry addict says:

The pH value would probably be something like negative….I don’t know, but there IS an acid stronger that that– fluoroantimonic acid(did someone already say that?). It is two to the power of 1019 times stronger than sulfuric acid, and, therefore, can even eat through glass. Isn’t this acid amazing?

October 17, 2011 at 4:08 am
(18) Same person says:

I am a person who like acids too!

December 5, 2011 at 10:33 am
(19) jon koyei says:

I was shocked to learn that fluoroantimonic is 20 quintillion times stronger than conc.sulphuric acid,thank u 4 ur information

December 5, 2011 at 10:38 am
(20) jon. koyei sekut says:

I was shocked to learn that fluoroantimonic is 20 quintillion times stronger than conc.sulphuric acid,guys this is the world strongest acid. thank u 4 ur information

February 21, 2012 at 10:27 am
(21) Yasir says:

Among the sulphuric,nitric,hydrocholoric, hydrobromic acids percholoric acid is strongest.

March 23, 2012 at 10:45 am
(22) Mike says:

Alien blood is the strongest, agrred.

November 20, 2012 at 12:25 pm
(23) satish says:

thank you ……. for information

January 24, 2013 at 10:43 am
(24) needhelp says:

why, other that pH, an acid strong

June 11, 2013 at 3:39 am
(25) tapan says:

my god! i never knew the diffrnce b/w strongness and corrosiveness.thanks for developing the concept

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