The scariest stuff

Hello and welcome to another Eccentric Sphere.

Today we talk about the craziest chemical I have ever heard of. It's so weird that it actually fits this blog really well.

It's called Chlorine trifluoride. If you ever see a sign with those two words on it, walk the other way.

Chlorine trifluoride was invented in the 1930's by German scientists who called it N-Stoff, or Substance-N. The Nazis were actually considering using it as a weapon, but ultimately thought it was too scary to use. Wrap your head around that....

Okay, so what's so dramatic about this gunk? Well, it burns what can't burn, while gassing the entire area and corroding what's left. I could copy-paste a lot of chemical jargon here, but the payoff is that this stuff is nuts. Chlorine trifluoride can be safely stored in containers made from steel, copper or nickel but that's about it. The stuff reacts with the metal and forms a surface of fluoride, which makes it safe. If you try to store it in anything else, you are screwed.

What Chlorine trifluoride does is burn. It burns everything, including glass, concrete, asbestos and things that have already burned – like ashes. It explodes in contact with water, even just moist air. It is so combustible that it ignites without an ignition source. The only recorded spill leaked out 900kg of the horror which burned through 30 cm of concrete and 90 cm of gravel underneath.

Once Chlorine trifluoride is on fire, only noble gasses like helium or nitrogen can put it out. Oxygen suppressors like halon or CO2 are useless as N-Stoff merrily keeps burning anyway, it produces that much oxygen on its own. Essentially, it burns better than pure oxygen.

This nasty stuff boils at 11.75 degrees Celsius (53 F) and it burns at a temperature of 2400 C (4352 F). 2400 Celsius is more than it may sound. Lava is about 1300 C, an steel melts at 1370 C. These temperatures combined with its ability to easily burn the nonburnable, means that a Chlorine trifluoride fire can't be contained.

To make matters even worse, (I told you this was bad) when Substance-N burns, it releases large amounts of acidic gas, namely hydrofluoric acid and hydrochloric acid. Both of these acids are extremely dangerous, and when released in gas form, will corrode or kill everything in the area. Everything that's not on fire, that is. It even corrodes gold, platinum and iridium, which are all extremely resistant to corrosion.

So, why does this chemical horror exist? Well, as I mentioned above, the Nazis wanted to use it as a weapon, but couldn't figure out how. Then, after the war, they considered using it as rocket fuel, since it burns so very well, and with no ignition time to speak of. NASA quickly decided that accidents when using rockets are dangerous enough as it is, without adding Chlorine trifluoride to the mix. One rocket scientist was asked what the best thing to use was when Substance-N spills. His answer: “A good pair of running shoes”.

Chlorine trifluoride is however used as a cleaning agent in the semiconductor industry, as well as a cleaning agent in Uranium power plants.

There we go, and that's all for today. Join me again next time and until then, have a great (and safe) week!