# ­xkcd thread **URL:** \ **Category:** Cafe Society\ **Tags:** comic-strips\ **Created:** [May 28, 2020, 12:57am UTC](https://boards.straightdope.com/t/xkcd-thread/854574 "2020-05-28T00:57:03Z")\ **Posts on this page:** 20\ **Page:** 275
**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:** [January 25, 2026, 10:47pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5483 "2026-01-25T22:47:42Z")
The Southern Lights, or Aurora Australis instead of the Northern Lights, or Aurora Borealis. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [January 25, 2026, 11:06pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5484 "2026-01-25T23:06:34Z")
A video about chlorine trifluoride [![](https://img.youtube.com/vi/dAhiqGZCwNQ/maxresdefault.jpg "Setting Fire to Glass - The "Nope" Chemical That is Chlorine Trifluoride") ](https://www.youtube.com/watch?v=dAhiqGZCwNQ) ---
**Author:** ![Al128](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/al128/32/16541_2.png) [@Al128](https://boards.straightdope.com/u/Al128)\ **Post date:** [January 25, 2026, 11:21pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5485 "2026-01-25T23:21:18Z")
… Of “Ignition!” fame!! Say no more. ---
**Author:** ![DesertDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/desertdog/32/11503_2.png) [@DesertDog](https://boards.straightdope.com/u/DesertDog)\ **Post date:** [January 26, 2026, 3:09am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5486 "2026-01-26T03:09:43Z")
> [@Peter\_Morris](#): > > Well I don’t. Please explain. [Fluorine: The element from hell](https://www.acsh.org/news/2016/02/14/fluorine-element-hell). > There is a [publication](http://web.ornl.gov/sci/psd/mst/rsg/pdf/HF_Safety_1.pdf), which, ironically (I don’t think they were kidding) is called “Working With HF [hydrofluoric acid] And Fluorine Safely.” You go first. > > - It reacts with virtually every element except Ar, He, and Ne. > - It is lethal at very low levels. > - Fire fighting The only practical way to extinguish a fluorine fire is to shut off the source of fluorine. > - Water and CO2 fire extinguishers only add fuel to fire. > - F2 is one of the most hazardous substances found in MSTD\* laboratories. > > \* Materials Science and Technology Division, Oak Ridge National Laboratory If that doesn’t make you feel safe enough, [another booklet](http://web.ornl.gov/~webworks/cpr/rpt/106423_.pdf) tells you how to protect yourself from it. Doesn’t sound all that bad: > > - Self-contained breathing apparatus with a full face piece > - Operated in the pressure demand mode or other positive pressure mode. ---
**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:** [January 26, 2026, 3:38am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5487 "2026-01-26T03:38:40Z")
And because the fluorine atoms in chlorine trifluoride are bonded more weakly to the central chlorine than they are to each other in F2, they actually attack other molecules even more vigorously than gaseous fluorine does. > [@DesertDog](#): > > self-contained breathing apparatus with a full face piece As in you need an oxygen tank; forget about even trying to filter gaseous fluorine out of the air. ---
**Author:** ![smithsb](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/smithsb/32/12107_2.png) [@smithsb](https://boards.straightdope.com/u/smithsb)\ **Post date:** [January 26, 2026, 4:34am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5488 "2026-01-26T04:34:58Z")
And then there’s FOOF. One of Derek Lowe’s “not in my lab” chemicals. [https://www.science.org/content/blog-post/things-i-won-t-work-dioxygen-difluoride](https://www.science.org/content/blog-post/things-i-won-t-work-dioxygen-difluoride) ---
**Author:** ![Q.Q.Switcheroo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/q.q.switcheroo/32/5713_2.png) [@Q.Q.Switcheroo](https://boards.straightdope.com/u/Q.Q.Switcheroo)\ **Post date:** [January 26, 2026, 7:26am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5489 "2026-01-26T07:26:43Z")
> [@Al128](#): > > as a southerner, who is also fighting ignorance, I’d like to show you my appreciacion for not calling an aurora … ahem … northern lights … b/c we have them too … just in the south May I see it? ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [January 26, 2026, 11:01am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5490 "2026-01-26T11:01:51Z")
> [@Pardel-Lux](#): > > It was **[John D. Clark](https://en.wikipedia.org/wiki/John_Drury_Clark)**. There are similarities, but he is no longer among us. He was an American [rocket fuel](https://en.wikipedia.org/wiki/Rocket_fuel) developer (thus the quote), [chemist](https://en.wikipedia.org/wiki/Chemist), and [science fiction writer](https://en.wikipedia.org/wiki/Science_fiction_writer). He was instrumental in the revival of interest in [Robert E. Howard’s](https://en.wikipedia.org/wiki/Robert_E._Howard) _[Conan](https://en.wikipedia.org/wiki/Conan_the_Barbarian)_ stories and influenced the writing careers of [L. Sprague de Camp](https://en.wikipedia.org/wiki/L._Sprague_de_Camp), [Fletcher Pratt](https://en.wikipedia.org/wiki/Fletcher_Pratt), and other authors. He had an interesting life. I do not think that name is so obscure among this crowd. His book is well worth reading: [https://library.sciencemadness.org/library/books/ignition.pdf](https://library.sciencemadness.org/library/books/ignition.pdf) ---
**Author:** ![Pardel-Lux](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pardel-lux/32/20182_2.png) [@Pardel-Lux](https://boards.straightdope.com/u/Pardel-Lux)\ **Post date:** [January 26, 2026, 12:56pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5491 "2026-01-26T12:56:19Z")
Yes, that is the book the cite upthread is from: pages 73 - 74. And a very nice _In Re_ by Isaac Asimov. Thanks for the link! Those are the things the internet was for, before it turned into a cesspit of asocial media. Good that some of the good stuff is still around. ---
**Author:** ![Norse](https://avatars.discourse-cdn.com/v4/letter/n/a9adbd/32.png) [@Norse](https://boards.straightdope.com/u/Norse)\ **Post date:** [January 26, 2026, 1:12pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5492 "2026-01-26T13:12:39Z")
As @Pardel-Lux points out, it was J.D. Clark who wrote that. But Derek Lowe quotes that paragraph in [one of his “Things I won’t work with” blog articles](https://www.science.org/content/blog-post/sand-won-t-save-you-time). Clark’s book is hilarious, by the way. Strongly recommended. ---
**Author:** ![Mollie\_Magill](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mollie_magill/32/20882_2.png) [@Mollie\_Magill](https://boards.straightdope.com/u/Mollie_Magill)\ **Post date:** [January 26, 2026, 3:42pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5493 "2026-01-26T15:42:54Z")
I like Simon Whistler. He’s a good presenter, but looks funny without his beard. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [January 26, 2026, 4:01pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5494 "2026-01-26T16:01:45Z")
Chlorine trifluoride is one of the few substances whose effects are actually _worse_ than the fictional xenomorph blood in the _Alien_ movies. Not only only does it corrode through substances typically considered to be inert like glass, concrete, and _asbestos_, but it also sets them on fire, often explosively. ---
**Author:** ![Al128](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/al128/32/16541_2.png) [@Al128](https://boards.straightdope.com/u/Al128)\ **Post date:** [January 26, 2026, 5:03pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5495 "2026-01-26T17:03:10Z")
Highlight: it even “burns” … **ash** ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [January 26, 2026, 5:07pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5496 "2026-01-26T17:07:39Z")
There is nothing other than maybe CO2 that is so thoroughly oxidized that you can’t oxidize it even better if you apply a big enough hammer. ClF3 is just about the biggest hammer possible. Oxidation reactions generally being exothermic just adds to the fun. There are few anvils you can drop on your foot and laugh off; the smallest injury is a biggie. Likewise there are few substances you can combine with ClF3 and laugh off; more often the results are spectacularly unhealthy for everyone and everything right nearby. ---
**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:** [January 26, 2026, 5:25pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5497 "2026-01-26T17:25:51Z")
Perhaps naive of me but going by chemical formula alone I would think ordinary baking soda would be a good neutralizing agent if you had enough of it. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [January 26, 2026, 6:01pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5498 "2026-01-26T18:01:59Z")
> [@Lumpy](#): > > Perhaps naive of me but going by chemical formula alone I would think ordinary baking soda would be a good neutralizing agent if you had enough of it. Not even close. The chlorine trifluoride would react violently and explosively with sodium bicarbonate (NaHCO3), liberating the hydrogen and forming gaseous HF and HCl. Sodium bicarbonate works to put out ordinary fires because when it is heated, it undergoes spontaneously thermal decomposition to produce carbon dioxide, which displaces the oxygen needed for most fires. But chlorine trifluoride is its own oxidizing agent, and doesn’t need oxygen. So no help there either. ---
**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:** [January 26, 2026, 6:04pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5499 "2026-01-26T18:04:45Z")
Then what the heck is the sodium doing in that reaction if it’s not binding any of the halogens? ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [January 26, 2026, 6:16pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5500 "2026-01-26T18:16:12Z")
> [@Lumpy](#): > > Then what the heck is the sodium doing in that reaction if it’s not binding any of the halogens? I’m sure you’d get a variety of products in the reaction besides the aforementioned HF and HCl, including sodium fluoride and chlorine gas. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 26, 2026, 6:23pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5501 "2026-01-26T18:23:36Z")
It’s trivially true that there are some things that ClF3 can’t react with. Put it in with any substance, and let it react. Eventually, it’ll stop reacting. Whatever’s left when that happens is something that ClF3 won’t react with. The problem is that there’s not much else it won’t react with, and even a small amount of anything it does react with will release a lot of energy, and releases of energy often result in exposing more reactable material. ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [January 26, 2026, 6:24pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5502 "2026-01-26T18:24:52Z")
I do wish I could find a reliable (and free, I’m not paying for this) chemical reaction simulator that would accurately model the reaction, including the reaction products and thermal balance. (I assume this would be enthusiastically exothermic, but I would like to see the actual number.) [Previous page](https://boards.straightdope.com/t/xkcd-thread/854574.md?page=274) [Next page](https://boards.straightdope.com/t/xkcd-thread/854574.md?page=276)