Egg in a Bottle

Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★★☆ Some safety precautions required to perform safely

Categories: Heat, Pressure and Fluids

Alternative titles: Air Pressure Egg Trick, The Egg Squeeze Experiment

Summary

A peeled hard-boiled egg is placed on the neck of a bottle. When lit matches are dropped into the bottle, the heated air expands and some escapes. As the air cools, it contracts, lowering the air pressure inside. The higher outside air pressure pushes the egg into the bottle.

Procedure

Hard boil a medium-sized egg and peel it.
(Optional) Grease the bottle’s neck with a little vegetable oil.
Place the egg on the bottle’s neck to show that it cannot fit inside without force.
Light 3 matches and drop them into the bottle.
Quickly set the egg over the bottle’s mouth.
Watch as the egg is pushed into the bottle by outside air pressure.
To remove the egg, turn the bottle upside down and blow into it. The air pressure increases, pushing the egg back out.

Links

What is Air Pressure: Egg Demonstration - funsciencedemos:

📄 Egg in a Bottle - Science World: https://www.scienceworld.ca/resource/egg-bottle/

Variations

Use a small water balloon instead of the egg.
Replace matches with a rolled paper towel “wick” lit on fire and dropped in.
Perform the experiment upside down by attaching candles to the egg, lighting them, and placing the bottle over it to suck the egg upward.

Safety Precautions

Adult supervision required when using fire.
Handle matches and flames carefully to prevent burns.
Do not use glass bottles with thin walls (risk of breaking when heated).

Questions to Consider

How can we get the egg into the bottle without chopping it up? (By changing air pressure inside the bottle so outside air pushes it in.)
Why is an egg suitable for this experiment? Could we use a ping-pong ball or a golf ball? (The egg is soft and flexible, so it can deform slightly to fit through the opening. A hard ball cannot compress to fit.)
Does the egg get “sucked” into the bottle? Why or why not? (No, it is pushed in by higher outside air pressure.)
How else could you change the pressure of the air inside the bottle? (By heating the air with hot water, or cooling it rapidly.)
How will we get the egg out? How do we increase the pressure inside the bottle? (By blowing into the bottle to raise inside pressure, forcing the egg back out.)