The Disappearing Egg

This involves lots of heat, so be careful and do not try this alone! We guarantee you’ll be talking about this egg-speriment at school the next day.

Question: How can an egg get sucked into a bottle?

Materials:

  • 1 hard-cooked egg (see instructions for hard-cooking an egg below)
  • 1 container (a bottle or jar with the mouth just a little too small for the egg to fall inside – try an apple juice bottle, an old style glass milk bottle or a vase with a long, narrow neck)
  • Small saucepan or pot
  • Water
  • Hot pads or oven mitts
  • Clock or timer
  • Adult helper

 

Procedure:

1. Hard-cook a large egg and peel it. Click here for instructions.
2. Turn on the hot water tap and let it run until the water gets very hot.
3. Carefully fill the jar with hot water – get your adult helper’s help with this. Let the water sit in the jar for 3-4 minutes.
4. Carefully pour out the hot water into the sink. Again, your adult helper can help with this.
5. Very quickly, place the egg on top of the container. Begin chanting “Big bop, big drop, big bop, big slop!”
6. Watch. The egg will quickly be sucked into the jar.

What Happened – and Why?

Hot air takes up more space than cool air. The air inside the jar was hot. When the egg was placed on top of the jar, it kept any outside air from getting into it. As the air inside the jug cooled, it took up less space. The pressure inside the container dropped. Since there was more air pressure pushing down on the egg than pushing against it, the outside air forced the egg to be sucked into the jar.

Want to get the egg out of the bottle? Turn the jar upside down to allow the egg to roll back to the neck of the jar, then blow into the bottle. Air will go in around the egg and into the jar – thus increasing air pressure in the bottle. This will cause the egg to (watch out!) pop back out!