Nearly a million people have now watched the recent YouTube video “LN2 Explodes In Chemistry Experiment Gone Wrong”, and every single viewer has undoubtedly shaken their head, clucked their tongue, and thought to themselves, “What a couple of idiots.”
LN2 is liquid nitrogen; and contrary to popular perception, it’s a hazardous substance. Yes, everyone has seen it cause the volcano at the science fair to erupt quite spectacularly; but unfortunately, these seemingly innocuous demonstrations of LN2′s coolness — pun intended — cause people to forget that it can also be misused, mishandled, and very dangerous.
Top Three Things the YouTube Knuckleheads Did Wrong:
- They failed to treat liquid nitrogen with the proper caution and respect its due, based on the bodily harm it can inflict. Sealed containers become bombs when there is no way for pressure to escape. Pressures of over 40,000 pounds per square inch are possible. A pop bottle or a thermos with the lid on is simply asking for a trip to the ER.
- They failed to wear safety goggles or face shields, as liquid nitrogen can easily splash into your face while being poured, and exploding frozen projectiles can cause serious eye injury as well.
- They failed to wear to wear safety gloves, as skin contact with liquid nitrogen causes tissue damage within 1 – 2 seconds.
A Primer for the Safe Handling of LN2:
- Be sure there’s no way liquid nitrogen can become trapped inside your clothing against your skin.
- When touching any object that’s been cooled by liquid nitrogen, wear loose-fitting gloves that can be pulled off quickly in case liquid is accidently dripped or spilled inside of them.
- Use only approved, unsealed vessels to hold liquid nitrogen. As seen in this video, LN2 explodes in a sealed container.
- Never perform liquid nitrogen demonstrations in a small, poorly ventilated room or in a vehicle with the windows closed. It could displace enough oxygen to cause suffocation.
- Never dispose of liquid nitrogen by pouring it on the floor. The visible cloud that forms is harmless condensed water vapor; but the nitrogen gas also formed is invisible, odorless, and tasteless and can cause nitrogen asphyxiation — suffocation caused by exhaling carbon dioxide without resupplying oxygen.
- Do not store liquid nitrogen for long periods in an uncovered container (nor a totally sealed container). As the oxygen over the nitrogen circulates, liquid oxygen can form and build up to levels which can cause spontaneous fires to ignite on organic materials — even clothing. Eliminate any possible sources of ignition such as flames, sparks, static electricity, etc.
LN2 Safety Precautions for Educators
Students, whether children or teenaged risk-takers, tend to be very curious about liquid nitrogen. They also tend to be very tactile, so they will be tempted to reach out and touch it. As mentioned above, direct skin contact will cause severe, almost instantaneous frostbite (a cryogenic “burn”) on contact. This is the #1 safety precaution that must be prevented. Teachers must stress to their students the importance of not touching freshly frozen objects or the nitrogen itself; and set a good example by modeling the correct use of tongs when carrying LN2 and handling any object going into or out of it.
In case the worst should happen, teachers should familiarize themselves with the first aid instructions (excerpted from the Air Products Nitrogen Material Safety Data Sheet) for cryogenic burns:
- If nitrogen contacts a student’s skin or eyes, the frozen tissue should be flooded or soaked with tepid water. DO NOT USE HOT WATER.
- Burns which cause blistering or deeper tissue freezing should be seen promptly by a physician.
There are scads of very impressive and educational liquid nitrogen demonstrations that will delight students when performed safely with the appropriate gear and preparation. So have a little fun! Stick large flowers, like carnations, in LN2 and then crumble them in your hand. Freeze mini marshmallows and after waiting a few moments, allow every student to eat one, directing them to chew only with their mouths open. The vapors released are quite dramatic! Freeze a banana and use it to hammer in a nail. Turn small pieces of chalk into little hovercrafts. Liquid nitrogen can be a wonderful teaching tool, but be smart and be safe.