How do strong bases burn you?

Toxic, Disgusting, Fiery: The 10 Most Dangerous Chemicals

2. Help, the concrete burns! |

Asbestos, firebricks, glass - some materials are considered completely non-flammable. But this is often not entirely correct, because there is a substance that even sets bricks on fire: chlorine trifluoride (ClF3). In an accident in the 1950s, about a tonne of the fabric spilled onto the concrete floor and burned through 30 centimeters of concrete and another meter of sand and rubble in the foundation before the chemical was used up. Chlorine trifluoride reacts hypergolically with almost everything. This means that it immediately goes up in flames on mere contact, without the need for energy to start the reaction.

The reason for the remarkable aggressiveness is that chlorine trifluoride is a stronger oxidizing agent than oxygen itself. That is why it also attacks the normally incombustible oxides, such as the silicates in stones or glass. Only some metals withstand the substance - because a thin layer of metal fluoride forms on their surface, which protects the rest of the metal. Thanks to this so-called passivation alone, ClF3 store and transport at all.

Surprisingly, there is an industrial application for chlorine trifluoride: In chip manufacture, the gas is used to clean the apparatus for the gas deposition of semiconductor layers. Chlorine trifluoride was once tested as a rocket fuel and ammunition for flame throwers, but it was soon abandoned because of its notoriously difficult handling. ClF3 is a gas at room temperature, but liquefies below about eleven degrees Celsius and is therefore transported cooled, preferably in very small quantities. The fact that chlorine trifluoride immediately goes up in flames whenever the opportunity arises is just the beginning of the problems: When burned, products are created that are themselves so highly toxic and aggressive that they deserve a place on this list.