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Low Temperature Physics: Liquid Nitrogen. (page 2)

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Author: Jerry Silver

Balloon—filled with liquid nitrogen

  1. Pour a small amount (start with about 10 mL) of liquid nitrogen in a balloon.
  2. Tie a knot in the open end.
  3. Set the balloon on a table.
  4. Step back and make sure no one is near the (expanding) balloon and especially make sure no one's face is close to the balloon.
  5. Observe what happens as the balloon is exposed to the warmer air temperature.

Prescription container/Film canister

  1. Place the film canister (or a plastic prescription container with a snap-off lid) on a table top or on the floor. Do not use a prescription container with a screw-on or a child-proof lid that does not easily snap off with moderate force.
  2. Pour some of the liquid nitrogen into the plastic beaker.
  3. Pour some of the liquid nitrogen from the plastic beaker into the film canister. Fill the film canister about ¼ full with liquid nitrogen.
  4. Snap on the top.
  5. Stand back as pressure builds up in the container.

Cork gun

  1. Place the cork gun where it is aiming in a safe direction (and specifically not directed toward anyone's face).
  2. Pour about 50 mL of liquid nitrogen into the cylinder.
  3. Lightly place the cork in the open end of the cylinder. Do not jam the cork in so tightly that it cannot be pushed out by the pressure that will build up in the cylinder.
  4. Stand back. Pressure will build up as the liquid nitrogen evaporates.

Expected Results

The frozen banana and flowers will shatter. The solder will temporarily become much more spring-like. The air-filled balloon will shrink as the air inside contracts from the extreme cold, and then it will re-inflate as it warms up again. The liquid nitrogen-filled balloon will expand and possibly burst. The lids of the film canister/ prescription bottle will pop off. The cork will shoot out of the metal cylinder.

Why It Works

Objects become more brittle and contract from the extreme cold. As the liquid nitrogen evaporates, it occupies a much larger volume. For a given volume, the gas has a much larger pressure.

Other Things to Try

For many experimenters, liquid nitrogen may not be easily available on a daily basis. While you have a supply of liquid nitrogen available, you may want to consider doing the other projects that also require liquid nitrogen, such as Project 101 (effect of temperature on resistance) and Project 106 (superconductivity).

The Point

Liquid nitrogen provides an opportunity to explore low-temperature physics. This includes making normally elastic materials brittle. Materials cooled by liquid nitrogen contract. As liquid nitrogen evaporates, it expands.

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