Liquid Nitrogen Demo List
Directions, concepts, and questions
Guiding Questions:
1. How cold is Liquid Nitrogen?
2. How is molecular motion, and resulting phase changes, influenced by
temperature changes?
3. How is pressure related to molecular motion, volume, and temperature?
4. How does the water content in food and air affect their physical
properties?
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N2 balloon- Pour a small amount of liquid nitrogen into a plastic soda bottle. Pull
the neck of the balloon over the bottle mouth and hold it there as the nitrogen
becomes gaseous. Tie off the balloon.
o Concept: Density, states of matter, molecular motion, pressure
o Questions to ask:
 What is in the balloon?
 Will the balloon sink or float. Why?
 What happens to the molecules as they go from a liquid to a gas?
 Where is the pressure coming from to inflate the balloon?
Frozen balloon- Inflate a balloon by blowing into it. Tie it off. Pour some liquid
nitrogen into a bowl, and lightly push the balloon into the nitrogen. Continue
doing so until it is mostly deflated. Remove it from the nitrogen and let students
watch it inflate.
o Concept: temperature, pressure, molecular motion
o Questions to ask:
 Before putting it in the nitrogen: What do you think will happen?
 Why does it shrink?
 Why does it re-inflate?
Tennis Ball Canister Explosion- Place a small amount of liquid nitrogen in a
tennis ball canister, while the canister sits on a flat, stable surface. Quickly cap
the canister in one movement and stand back. Warning: Cap and canister will fly
around. Keep an area clear around demo site for safety.
o Concept: pressure, molecular motion, states of matter
o Questions to ask:
 What do you hypothesize will happen?
 Why does the cap fly off?
 What causes the ‘explosion’?
 How is molecular movement responsible for the explosion?
Whistling tea kettle- Pour some liquid nitrogen into a metal teakettle, with the
nozzle open, and put the lid on. Close the nozzle cap, and the kettle will emit a
high-pitched whistling noise.
o Concept: pressure, states of matter, molecular motion
o Questions to ask:
 Does this sound the same as when you boil water?
 What causes this sound?
 What gas is escaping?
 How much warmer is the kettle (room temperature) than liquid
nitrogen?
Colorado State University Chemistry Outreach
[email protected]
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Flower/lettuce smashing- Pour some liquid nitrogen into a bowl or small dewar.
Holding the stem, dip the flower/leaf into liquid nitrogen, and leave it there for 1020 seconds, to insure it freezes through all the way. Pull it out, and hit it firmly
and quickly on a solid surface, such as the tabletop or floor. Warning: always
wear padded gloves when handling because of the extreme temperatures.
Always wear safety glasses, as shards may fly up upon smashing. Always have
a tarp/pool/blanket to smash on for easy cleanup.
o Concept: surface area, change of states
o Questions to ask:
 Why does the flower smash?
 What is in the flower or what part of the flower is actually freezing?
 How long (in comparison) do you think it would take to freeze
something thicker, like a banana?
Linden-Frost Effect: - Have small amount of liquid nitrogen in a small dewar or
bowl. Hold your hand out at arm's length with your palm facing down and fingers
spread apart. Quickly pour a SMALL amount of liquid nitrogen onto the back of
your hand. Warning: Make sure to remove all rings, bracelets, watches, etc.
from your hand before performing this demo. Do NOT do this to students, as
there is the potential for small contact burns.
o Concept: Linden frost effect, phase changes
o Questions to ask:
 What do you think would happen if I stuck my hand into the liquid
nitrogen?
 What do you think would happen if I poured the liquid nitrogen
over my hand?
 Why did I not freeze my hand?
 How much warmer is my hand than the liquid nitrogen?
Frozen Cheetos and Marshmallows- Pour liquid nitrogen into an easy to access
bowl. Pour marshmallows/Cheetos into the bowl, and lightly push them down into
the nitrogen with a spoon. Explain the rules to students: 1) play hot potato with
the food in their hand for 15 seconds until it has warmed up enough to eat. 2) If it
freezes to your tongue, wait and let it warm up, don’t rip 3) chew with your mouth
open!
o Concept: air pockets (water content in air), phase changes
o Questions to ask:
 Do these food have water in them? So why do they freeze? (Air
pockets)
 What is the gas you see escaping when chew?
 Why is it okay to eat food that has been in Liquid Nitrogen?
Ping-pong ball and water- Poke a small hole in a ping-pong ball with a
thumbtack beforehand. Fill a small cup up with warm water all the way to the top.
Place the cup on the table. Put the ping-pong ball in a dewar or bowl of Liquid
nitrogen and gently submerge it using a spoon. After about 5-10 seconds, scoop
it out and place it the cup of water. It should spin around in circles and
(potentially) fly up and hover.
o Concept: phase changes, molecular motion, pressure
o Questions to ask:
 What is causing the ball to spin around like this?
 Why are we using warm water?
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Freezing elasticity- Submerge rubber bands, bouncy balls, racket balls, etc. in
the nitrogen. This causes them to lose most of their elasticity. Experiment with
trying to bouncy or pull them. If you throw them hard enough, they may also
break apart!
o Concept: rubber elasticity, temperature
o Questions to ask:
 Is the rubber freezing, or is it the low temperature that decreases
elasticity?
 Where in life do you see this happen?
Floating chalk- Soak a piece of chalk in liquid nitrogen. Take it out and place it on
a smooth surface. It will appear to hover or float above the surface as the gas
escapes from the pores in the chalk.
o Concept: phase change, pressure, Linden-frost effect
o Questions to ask:
 What causes the chalk to float?
 Is the chalk solid?
 What effect is this similar to that we saw earlier?
Egg in bottle- Put hard-boiled egg (deshelled) on top of a plastic/glass bottle.
Submerge the bottom of bottle in nitrogen, and the egg will be sucked into the
bottle.
o Concept: Pressure, Molecular motion, temperature
o Questions to ask:
 What creates the vacuum that sucks the egg in?
 What happens to the air molecules in the bottle when submerged
in the nitrogen?
Warm water and LN2- Have a bowl of warm or near boiling water. Carefully pour
a little liquid nitrogen into the bowl to create a really epic looking fog effect.
o Concept: phase change
o Questions to ask:
 What is the fog we are seeing? Gaseous water or Nitrogen?
 What is the temperature difference between the two liquids?
Banana hammer- Poke a nail or stick into a banana, leaving enough out to act as
a handle. Freeze a banana in liquid nitrogen. This will take a while because of
how little surface area there is relative to volume. Pull the banana out, and use it
to hammer a nail into a piece of 2x4 wood. Be careful to not smash the banana
violently against the nail or it will crack.
o Concept: water content, phase change, density
o Questions to ask:
 Why did it take so long to freeze the banana?
 Why is this banana capable of acting a hammer?
 Can you think of other instances where temperature can change
the function of an object?
Colorado State University Chemistry Outreach
[email protected]
Risky demo:
 Hot dog finger and a hammer- If you are feeling really spunky, relatively brave,
and you want to pull a prank on your students, you can use this demo. In a large,
rubber cleaning glove, place a hot dog and a squirt of ketchup in one of the
fingers. Pretend to slide your hand into the glove (actually keep all your fingers in
the palm area) and dip the fingers- and hot dog- in the nitrogen. Have a student
you trust use a hammer to smash your ‘finger’ (the hotdog) with a hammer. It will
look bloody and meaty with the ketchup. If you act and play it up, this can be
quite the show! Warning: If you do get a student to help, it is wise to warn them
about what is actually happening beforehand. Also, be mindful about doing this if
there is anyone who may react badly, including fainters or people who have
reduced hand/arm abilities.
Additional recommended demo sources:
http://www.semcto.com/docs/Liquid_Nitrogen.pdf
http://education.jlab.org/frost/