Liquid nitrogen - super cold!

Ultra Cold LN2 Replacement that will instantly freeze anything!

NOTE: THIS EXPERIMENT IS HIGHLY HAZARDOUS AND CAN RESULT IN INJURY OR DEATH. IT IS NOT INTENDED TO BE CONDUCTED BY CHILDREN BUT RATHER, SHOULD BE CONDUCTED BY SICENCE TEACHERS ONLY!

Liquid nitrogen, represented by the equation LN2, is often used in higher level science experiments. In this experiment, we’ll create a liquid with the same “ultra cold” properties found in liquid nitrogen.

Liquid nitrogen - super cold!You’ll need two plastic bottles, one slightly smaller than the other.

  1. Cut the tops off of both bottles. Cut a few inches down so all of the curved neck of the bottle is removed.
  2. In the smaller bottle poke a bunch of holes in the sides and bottom of the bottle.
  3. Now place the smaller bottle inside of the larger one. There should be about a finger’s width of space in between them.
  4. Pour the dry ice pellets into the space between the bottles. Keep the smaller bottle centered evenly so there is an equal amount of pellets on all sides.
  5. Pour the alcohol into the space between the bottles making sure it runs over the dry ice (so it gets cooled). Note the fog that is produced.
  6. Now pour about 3 inches of alcohol into the center bottle. The alcohol in the center bottle will thicken (if you don’t use 99% alcohol it will really thicken). Bingo!  You have some ultra cold liquid!

Note: the alcohol will be extremely cold – if it comes into contact with your skin or any other part of your body, it will cause instant and EXTREME frostbite which will be very painful and dangerous!

Parent/Teacher/Advanced Notes

Liquid nitrogen is the liquid produced industrially in large quantities by fractional distillation of liquid air and is often referred to by the abbreviation, LN2. It is pure nitrogen, in a liquid state.

At atmospheric pressure, liquid nitrogen boils at 77 K (-196 °C/-321 °F), and is a cryogenic fluid which can cause rapid frostbite on contact with living tissue. When appropriately insulated from ambient heat, liquid nitrogen can be stored and transported, for example in vacuum flasks. Here, the very low temperature is held constant at 77K by slow boiling of the liquid, resulting in the evolution of nitrogen gas. Depending on the size and design, the holding time of vacuum flasks ranges from a few hours to a few weeks.

Liquid nitrogen can easily be converted to the solid by placing it in a vacuum chamber pumped by a rotary vacuum pump. Liquid nitrogen freezes at 63 K (-210 °C/-346 °F). Despite its reputation, liquid nitrogen’s efficiency as a coolant is reduced by the fact that it boils immediately on contact with a warmer object, enveloping the object in insulating nitrogen gas. This effect is known as the Leidenfrost effect and applies to any liquid in contact with an object significantly hotter than its boiling point. More rapid cooling may be obtained by plunging an object into a slush of liquid and solid nitrogen than into liquid nitrogen alone.

Commercial liquid nitrogen storage containerLiquid nitrogen is a compact and readily transported source of nitrogen gas without pressurization. Further, its ability to maintain temperatures far below the freezing point of water makes it extremely useful in a wide range of applications, primarily as an open-cycle refrigerant, including:

  1. in cryogenics
  2. as a source of very dry nitrogen gas
  3. the immersion freezing and transportation of food products
  4. the cryopreservation of blood, reproductive cells (sperm and egg), and other biological samples and materials
  5. as a coolant for overclocking a central processing unit, a graphics processing unit, or another type of computer hardware
  6. as a method of freezing water pipes in order to work on them in situations where a valve is not available to block water flow to the work area.
  7. in cryotherapy for removing unsightly or potentially malignant skin lesions such as warts and actinic keratosis.
  8. in the process of promession, a way to dispose of the dead.
  9. cooling a high-temperature superconductor to a temperature sufficient to achieve superconductivity.
  10. the cryonic preservation of humans and pets in the hope of future reanimation.

The dangers of liquid nitrogen

Since the liquid to gas expansion ratio of this substance is 1:694, a tremendous amount of force can be generated when liquid nitrogen boils off for whatever reasons. In a well-known accident in 2006 at Texas A&M University, the pressure-relief devices of a tank of liquid nitrogen were sealed with brass plugs. As a result, the tank failed catastrophically, and exploded. The force of the explosion was sufficient to propel the tank through the floor/ceiling immediately above it.

Due to its extremely low temperature, careless handling of liquid nitrogen may result in cold burns. It should be also borne in mind, that as liquid nitrogen evaporates it will reduce the oxygen concentration in the air and might act as an asphyxiate, especially in confined spaces. Nitrogen is odorless, colorless and tasteless, and may produce asphyxia without any sensation or prior warning. Lab worker James Graham famously died from asphyxiation after liquid nitrogen spilt in his laboratory in 1999.

Experiment Supplies

Supplies: Plastic bottle, Alcohol (Pure or 99%), Dry ice

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