# What is the most corrosive "acid" known? **URL:** \ **Category:** Factual Questions\ **Created:** [August 23, 2003, 6:29pm UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195 "2003-08-23T18:29:43Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Muad\_Dib](https://avatars.discourse-cdn.com/v4/letter/m/35a633/32.png) [@Muad\_Dib](https://boards.straightdope.com/u/Muad_Dib)\ **Post date:** [August 23, 2003, 6:29pm UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/1 "2003-08-23T18:29:43Z")
I was thinking about everyones favorite alien the Xenomorph the other day and their particularly nasty “acid” blood (I put acid in quotes because all we know is that it is corrosive, not necesarily acidic). Do such increadibly corrosive substances exist? Are their chemicals that, only a few onces, couold eat through several inches of steel in seconds? What are these materials and how do they work? ---
**Author:** ![SnoopyFan](https://avatars.discourse-cdn.com/v4/letter/s/d07c76/32.png) [@SnoopyFan](https://boards.straightdope.com/u/SnoopyFan)\ **Post date:** [August 23, 2003, 6:35pm UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/2 "2003-08-23T18:35:31Z")
I’m no scientist but I’m thinking that stomach acid, with its Ph of 1.5, could do some damage to metal. ---
**Author:** ![Dragon\_Phoenix](https://avatars.discourse-cdn.com/v4/letter/d/bcef8e/32.png) [@Dragon\_Phoenix](https://boards.straightdope.com/u/Dragon_Phoenix)\ **Post date:** [August 23, 2003, 6:42pm UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/3 "2003-08-23T18:42:08Z")
Hydrogen fluoride with water is extremely powerful, even attacking glass. A mixture of nitric acid and sulphuric acid is not ‘bad’ either. Both of them are far stronger than stomach acid. ---
**Author:** ![Tapioca\_Dextrin](https://avatars.discourse-cdn.com/v4/letter/t/3d9bf3/32.png) [@Tapioca\_Dextrin](https://boards.straightdope.com/u/Tapioca_Dextrin)\ **Post date:** [August 23, 2003, 7:16pm UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/4 "2003-08-23T19:16:26Z")
You do not want to mess with [Hydrofluroic acid](http://www.mednets.com/index.cfm/fuseaction/articles_hydrogen_fluoride_poisoning_and_exposure_toxicology-Hydrogen-Fluoride/active_search/1/get_search_results.htm) (it’s OK, no gruseome pics). There is no substance that burns through several inches of steel in a few seconds. I believe you need a 1920’s style death ray fo that. ---
**Author:** ![Dragon\_Phoenix](https://avatars.discourse-cdn.com/v4/letter/d/bcef8e/32.png) [@Dragon\_Phoenix](https://boards.straightdope.com/u/Dragon_Phoenix)\ **Post date:** [August 23, 2003, 7:24pm UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/5 "2003-08-23T19:24:34Z")
And by the way, Hydrogen fluoride = Hydrofluroic acid … ---
**Author:** ![Rysto](https://avatars.discourse-cdn.com/v4/letter/r/ecccb3/32.png) [@Rysto](https://boards.straightdope.com/u/Rysto)\ **Post date:** [August 23, 2003, 8:00pm UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/6 "2003-08-23T20:00:06Z")
Nitpick: _Aqueous_ Hydrogen Fluoride = Hydrofluoric Acid ---
**Author:** ![chaoticbear](https://avatars.discourse-cdn.com/v4/letter/c/f07891/32.png) [@chaoticbear](https://boards.straightdope.com/u/chaoticbear)\ **Post date:** [August 23, 2003, 8:22pm UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/7 "2003-08-23T20:22:09Z")
hmmm. strongest acid i think is perchloric:HClO4… but aqua regia is stronger yet… mixture of concentrated hydrochloric and sulfuric… ---
**Author:** ![wolf\_meister](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolf_meister/32/15202_2.png) [@wolf\_meister](https://boards.straightdope.com/u/wolf_meister)\ **Post date:** [August 23, 2003, 8:25pm UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/8 "2003-08-23T20:25:01Z")
I believe **perchloric acid** is the strongest of all. **Dragon** I believe the mixture you described (sulphuric and nitric acid) is aqua regia (royal water) and can dissolve gold. ---
**Author:** ![wolf\_meister](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolf_meister/32/15202_2.png) [@wolf\_meister](https://boards.straightdope.com/u/wolf_meister)\ **Post date:** [August 23, 2003, 8:29pm UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/9 "2003-08-23T20:29:18Z")
Darn **chaotic** - you beat me to the punch. Great minds think alike though huh ?? ---
**Author:** ![wolf\_meister](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolf_meister/32/15202_2.png) [@wolf\_meister](https://boards.straightdope.com/u/wolf_meister)\ **Post date:** [August 23, 2003, 8:33pm UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/10 "2003-08-23T20:33:11Z")
and chaotic I think we BOTH got the aqua regia mixture wrong. It is Nitric acid and Hydrochloric acid. [http://www.bartleby.com/65/aq/aquaregi.html](http://www.bartleby.com/65/aq/aquaregi.html) ---
**Author:** ![chaoticbear](https://avatars.discourse-cdn.com/v4/letter/c/f07891/32.png) [@chaoticbear](https://boards.straightdope.com/u/chaoticbear)\ **Post date:** [August 23, 2003, 8:33pm UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/11 "2003-08-23T20:33:32Z")
huh. aqua regia is nitric and HCL… [more info, with a dissolving gold video](http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA3/MAIN/AQREGIA/PAGE1.HTM) ---
**Author:** ![patchbunny](https://avatars.discourse-cdn.com/v4/letter/p/dc4da7/32.png) [@patchbunny](https://boards.straightdope.com/u/patchbunny)\ **Post date:** [August 23, 2003, 8:41pm UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/12 "2003-08-23T20:41:11Z")
The most acidic material I’ve ever come across is in the [Iron Mountain mines](http://www.usgs.gov/public/press/public_affairs/press_releases/pr1178m.html) near Redding, California. It’s an old copper/zinc/gold/silver/pyrite mine that’s been abandoned for a number of years now, and is on the Superfund cleanup list. Researchers exploring the mine to determine the source of low acidity groundwater discharge found waters with pH levels as low as -3.6. :eek: Quoting from the above web page: > [@](#): > > Alpers and other members of the underground sampling team had to contend with dangerous conditions in the mine workings. The temperature was more than 120 degrees Fahrenheit, humidity approached 100 percent, random rock falls from the 40-foot ceiling were a common occurrence, and extremely acid water was dripping everywhere. Huge stalacite-stalagmite structures, composed of rhomboclase and other iron sulfate minerals, spanned from floor to ceiling in the mine opening, where the most acidic waters were found. Rhomboclase, a rare mineral, is a solid form of sulfuric acid and ferric iron sulfate. I don’t think Tom and Becky would have lasted long in there. –Patch ---
**Author:** ![chaoticbear](https://avatars.discourse-cdn.com/v4/letter/c/f07891/32.png) [@chaoticbear](https://boards.straightdope.com/u/chaoticbear)\ **Post date:** [August 23, 2003, 8:54pm UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/13 "2003-08-23T20:54:02Z")
> [@](#): > > \*Originally posted by wolf\_meister \* > \*\*and chaotic I think we BOTH got the aqua regia mixture wrong. > > It is Nitric acid and Hydrochloric acid. > > [http://www.bartleby.com/65/aq/aquaregi.html](http://www.bartleby.com/65/aq/aquaregi.html) \*\* i noticed that right before you posted :} ---
**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\ **Post date:** [August 24, 2003, 2:39am UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/14 "2003-08-24T02:39:04Z")
> [@](#): > > \*Originally posted by SnoopyFan \* > \*\*I’m no scientist but I’m thinking that stomach acid, with its Ph of 1.5, could do some damage to metal. \*\* Acidic stomach contents are pretty mild compared to things like nitric and hydrofluoric acid. Vomiting up stomach acid just burns a bit, and it takes months or years of chronic exposure to the acids to make an esophagus scarred or pre-cancerous. But if drinking hydroflouric acid doesn’t kill you on the way down, vomiting it back up pretty much ensures it will finish the job. ---
**Author:** ![wolf\_meister](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolf_meister/32/15202_2.png) [@wolf\_meister](https://boards.straightdope.com/u/wolf_meister)\ **Post date:** [August 24, 2003, 2:45am UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/15 "2003-08-24T02:45:42Z")
**chaotic** I had a feeling you did notice it - but at least I “beat you to the punch” on that one. ---
**Author:** ![Muad\_Dib](https://avatars.discourse-cdn.com/v4/letter/m/35a633/32.png) [@Muad\_Dib](https://boards.straightdope.com/u/Muad_Dib)\ **Post date:** [August 24, 2003, 8:12am UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/16 "2003-08-24T08:12:16Z")
So that is it? There is no “concentrated molecular acid” that can eat through several decks of a starship in less than a minute? ---
**Author:** ![Desmostylus](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@Desmostylus](https://boards.straightdope.com/u/Desmostylus)\ **Post date:** [August 24, 2003, 10:06am UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/17 "2003-08-24T10:06:18Z")
Earlier threads: [Acid Test](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=155457) [So - what’s the strongest acid?](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=137118) ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [August 24, 2003, 12:33pm UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/18 "2003-08-24T12:33:55Z")
It’s not a liquid at room temperature so it’s probably not an “acid” in the sense we’re discussing, but pure gaseous fluorine is probably the most aggressive corrosant in existence. It will attack anything except noble gases and substances that are already completely fluoridated. ---
**Author:** ![handy](https://avatars.discourse-cdn.com/v4/letter/h/b5a626/32.png) [@handy](https://boards.straightdope.com/u/handy)\ **Post date:** [August 24, 2003, 3:35pm UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/19 "2003-08-24T15:35:03Z")
It would depend what you meant by ‘strongest acid’ or ’ corrosive’ as some acids are actually quite mild unless you concentrate them. There is something called ‘Magic acid’, FHSO3-SbF5, aka ‘superacid’ which ranks pretty high. ---
**Author:** ![bizzwire](https://avatars.discourse-cdn.com/v4/letter/b/958977/32.png) [@bizzwire](https://boards.straightdope.com/u/bizzwire)\ **Post date:** [August 24, 2003, 3:55pm UTC](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195/20 "2003-08-24T15:55:33Z")
Dammit, \*\* Handy!!\*\* beat me to the punch. Also, can something actually have a _negative_ pH? wouldn’t the lowest they go (for monobasic acids, at least) be a pH of 0 (i.e. fully dissociated)? [Next page](https://boards.straightdope.com/t/what-is-the-most-corrosive-acid-known/197195.md?page=2)