I have had my eyes on this egg in a bottle experiment for a long time now. Basically, you take a hard-boiled egg, set it on the neck of a bottle, and then magically, the air pressure difference sucks the egg into the bottle.
The egg in the bottle experiment sounded so fun! But for the life of me, I could not find a bottle that would work. The neck of a water bottle was way too small and a mason jar was way too big.
Eureka! Instead of trying to find a bottle that would work for the air pressure experiment, why not switch out the egg and save it for a healthy snack? By using a water balloon instead of an egg, you can use whatever glass container you have around the house because you can make the water balloon as big as you would like!
How to Suck a Water Balloon into a Jar
1. Fill the water balloon with water until it’s slightly bigger than the neck of the bottle or jar (we used a Mason jar). Tie the balloon.
2. Set the jar on a flat surface and place the water balloon on the neck of the jar.
3. Have your kids push down on the balloon to show that you cannot push it into the bottle.
4. Light a match and drop it into the jar.
5. Wait until the fire gets a little bigger and then place the water balloon over the mouth of the jar.
6. The fire will extinguish and the water balloon will get sucked into the jar.
7. To get the water balloon out of the jar, turn the jar sideways and then release the suction by placing a finger between the balloon and the jar.
As with the cloud in a jar experiment, my kids loved watching me lighting the match (adults only please!). Fire is always so exciting! Then they shrieked every time the water balloon started bouncing up and down due to the fire in the jar. We repeated this experiment over a dozen times, and the kids were equally delighted every single time!
We tried our hardest to get the entire water balloon in the jar. We tried water balloons of different sizes and dropping more than one lit match in the jar. There were a few times we got really close, but no cigar.
There are a few ways that I believe you could get the entire water balloon to fall into the jar but we ran out of time (and sunlight):
- Getting a bigger fire in the jar. You can do this by lighting 3 or 4 matches (or more?) at a time and dropping them into the jar. Please be careful and watch your fingers! Since our Mason jar wasn’t that tall, I was worried that the flame would touch the bottom of the balloon and pop it.
- Setting a piece of paper on fire and dropping it into the jar instead of a match. This would create a bigger flame as well.
- Wetting the outside of the water balloon. Just rub some water on the surface of the balloon to make it more slippery.
- Similarly, try using oil on the water balloon.
Science Behind Balloon in a Jar Experiment
Let’s start with why you can’t push the water balloon into the jar in the first place. When you place the balloon over the opening, the air inside the jar is trapped. There is no outlet for the air since the balloon has sealed the opening. Therefore, you can’t force the water balloon into the jar no matter how hard you push.
At this point, the air pressure inside the jar is the same as the air pressure outside. So the balloon will continue to sit at the opening without moving.
When you drop a lit match into the jar, the air inside heats up and expands quickly. If the fire is big enough, the expanding air will try and push the water balloon aside to escape from the jar. You will actually see your water balloon vibrating!
Eventually, the fire will consume all the oxygen inside the jar, and the flame will go out. The air inside the jar cools and contracts. Since the air inside now takes up less space, the air pressure drops.
With lower air pressure inside the jar than outside, the air from the outside wants to rush in to equalize the air pressure. But the water balloon is in the way! As a result, the outside air pushes on the water balloon and the water balloon gets sucked into the bottle.
Ghost in a Jar
If you are doing this experiment close to Halloween, or if your kids are just a fan of the paranormal, use a white water balloon and draw a ghost face on it!
Show your kids how you can magically suck the ghost into the jar after they fail to push it in by hand. Time for some spooky fun!
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