Egg in a Bottle
The Experiment
Drop three lit matches into a glass bottle (ideally, an old-fashioned milk bottle) and immediately place a peeled, hard-boiled egg vertically on the mouth of the bottle. Watch the egg get sucked through the narrow opening.
The Explanation
The flames heat and expand the air, and some of the air escapes out of the mouth of the bottle. As the matches go out, the air cools and contracts, which causes the pressure outside the bottle to be greater than the pressure inside the bottle. This pressure difference causes the egg to be pulled inside.
Alka Seltzer Rockets
The Experiment
Place 1 tablespoon vinegar and 1/2 Alka Seltzer tablet inside a film canister (a canister with a lid that fits inside the rim is best). Close the lid securely, then stand back and prepare for blast off!
The Explanation
The Alka Seltzer combined with the vinegar causes a chemical reaction that releases carbon dioxide gas. That gas increases the pressure inside the small space and drives the rocket to the ceiling.
Swimming Raisins
The Experiment
Drop 3 raisins into a glass or bottle filled halfway with sparkling water. Wait and watch.
The Explanation
The carbonation in the water contains dissolved carbon dioxide gas that collects on the bumpy surface of the raisins, carrying them to the surface. Once the raisins reach the surface, the gas is released into the air, and the raisins sink again.
Geyser Eruption
The Experiment
In your backyard, drop as many Mentos as possible into a half-liter bottle of Coke and then back away as fast as possible. Be prepared for a major eruption and some sticky cleanup.
The Explanation
There's some debate as to what causes this explosion, and the explanation is quite lengthy. In short, the ingredients in the Mentos (gelatin and gum arabic) dissolve and break the surface tension, which means it takes less work to form new bubbles. And each Mento has thousands of tiny pores on the surface in which carbon dioxide bubbles form. When the heavy Mentos sink to the bottom, carbon dioxide is released, which causes the jet stream.
Magnetic Pull
The Experiment
Draw a maze on a piece of cardboard. Place a paper clip on top of the cardboard and put a magnet under the cardboard in the same spot as the paper clip. Try to move the paper clip through the maze by moving the magnet below. Now, drop the paper clip in a glass of water. Place the magnet outside the glass (near the paper clip) and try to guide the paper clip to the of the glass by moving the magnet.
The Explanation
This may seem like magic to your kids, but it's pretty simple. The magnet guides the paperclip through the maze and pulls it through the water because the attraction is strong enough to pull magnetic material (the paper clip) through a nonmagnetic material—the cardboard and glass.
