Chlorine Trifluoride : The Compound That Can Even Set Fire to Glass

Chlorine Trifluoride : The Compound That Can Even Set Fire to Glass

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Chlorine trifluoride (ClF3) is toxic, corrosive, and incredibly reactive with practically every element on the planet. The chemical is rather useful as a high-energy fluorinating agent or incendiary material. Although, the same properties which make it useful can also turn it sinister extremely quickly if the chemical is misused in any way.

Spacefill model of chlorine trifluoride [Image Source: Wikipedia]

The History of Chlorine Trifluoride

Having a compound which reacts violently with practically everything seems nothing short of absurd, though its powerful oxidation properties can be useful in some industrial practices.

Fluorine (F2) currently retains the title as the most powerful oxidizing agent of all known elements. Though, back in 1930, scientists Otto Ruff and H. Krug isolated a compound which would prove to be more reactive than fluorine. The liquid is extremely hypergolic with most compounds (self-igniting) making it an ideal fuel for flamethrowers.

At the time World War II was raging. Many countries were researching chemical weapons which were highly effective and could be manufactured cheap. ClF3 naturally intrigued scientists because of how easy it is to manufacture and how devastatingly effective it was. Once Germany discovered the compound they used it to make incredibly powerful incendiary bombs. The compound became so effective they began to produce the compound in tonnage quantities.

Though it was easily produced, only about 30-tons were ever produced. The chemical’s instability and reactive properties made it incredibly dangerous to handle.

Fortunately, since the war, the compound has been banned under the Chemical Weapons Convention. Though the pact did not stop the production of the compound entirely.

What makes it so deadly?

When ClF3 comes into contact with virtually any element, it evaporates into a toxic gas. Though, even if it decomposes it still produces hydrofluoric and hydrochloric acid, typically in steam form. If it ignites (which it does easily), it burns at over 2,400 degrees Celsius. As it turns out, the chemical is more oxidizing than oxygen itself, making it an extremely effective explosive. Essentially, in lamens terms, chlorine trifluoride can set fire to famously inflammable materials including things like sand, glass, or even asbestos. Even compounds which have already been burnt can be reignited, like a pile of ash.

Upon contact with water, CLF3 reacts explosively. Unfortunately for humans, water is an element humans are mostly comprised of. Once in contact with human skin, the mixture quickly ignites. Pouring water on it only provides more fuel for it to burn. Once ignited, it is nearly impossible to extinguish. Typically the best course of action during a spill is to evacuate the area and let the chemical wreak its havoc. The corrosive gasses which are created are easily carried by the wind. Any metals that come into contact with it become severely rusted.

The time a TON of ClF3 was spilled

Throughout the late 1940s on towards the early 1950s, scientists were investigating using fluorinating compounds as potent oxidizers to be used in liquid-fueled rockets. In 1948, the U.S. successfully conducted the first test where ClF3 was used on a liquid propellant rocket motor. Further testing proved favorable results promoting further production of ClF3.

Manufacturing a rocket with an oxidizing agent that reacted violently with practically any element requires particularly careful consideration into every material which is each used. Each part was meticulously crafted, cleaned, and passivated to prevent any parts from spontaneously corroding or igniting. Though safety was heavily considered, the compound remained extremely hazardous.

During the era of the creation of liquid rocket propellant, disaster struck for the first time involving ClF3. A one-ton steel container was being prepped to be loaded with liquid ClF3 for a large shipment. To reduce the chances of ignition, the tank was cooled with dry ice making the compound safer to handle. However, the effects of the dry ice on the container was not considered. The incredibly cold temperatures embrittled the steel containers wall, compromising its structural integrity. The weakened container cracked as it was being transferred onto a dolly, allowing the product to uncontrollably leak out. The accident lead to the release of 907 kg of ClF3 onto the ground. The chemical quickly ate through 30 cm of concrete before continuing to dissolve another 90 cm of gravel underneath.

Deadly fumes including chlorine trifluoride, hydrogen fluoride, chlorine, as well as many others caused severe corrosion to everything the chemicals came into contact with.

Regular candle wax is unreactive to ClF3

Chlorine trifluoride is a chemical which should only be handled by professionals. Once it turns into a gas, ClF3 is colorless with a sweet and pungent odor. There are only a few chemicals which remain completely unreactive with chlorine trifluoride. Shockingly, one of them is regular candle wax. Without a proper container, the compound could react violently which can prove to be fatal.

Though, some YouTubers have taken the risk to show how dangerous the chemical is. YouTuber Simon Whistler discussed the extreme dangers of ClF3 on his channel Today I Found Out. In the video, he talks about the volatile nature of the compound and he demonstrates how the chemical readily ignites most compounds- including glass.

In the words of John Clark, chlorine trifluoride

”is, of course, extremely toxic, but that’s the least of the problem. It is hypergolic with every known fuel, and so rapidly hypergolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water-with which it reacts explosively.” He continues, “It can be kept in some of the ordinary structural metals-steel, copper, aluminum, etc.-because of the formation of a thin film of insoluble metal fluoride which protects the bulk of the metal, just as the invisible coat of oxide on aluminum keeps it from burning up in the atmosphere. If, however, this coat is melted or scrubbed off, and has no chance to reform, the operator is confronted with the problem of coping with a metal-fluorine fire. For dealing with this situation, I have always recommended a good pair of running shoes.”

[Featured Image Source: Pixabay]