This is a super simple science experiment, but one that’s impressive to young kids anyway. It’s so easy, I figured I had no excuse for not doing it at least once with my kids. I started by telling them we were going to blow up a balloon without having to blow into the balloon. (I guess technically I could have just gotten out a balloon pump at that point, but that would have been pretty anticlimactic.)
All this experiment requires is a little baking soda and vinegar, the same supplies that are used for numerous kid science experiments ranging from the mini volcano to the exploding sandwich bag. The reason it works is that baking soda (a weak base) and vinegar (an acid) react when placed in contact with each other and release carbon dioxide gas.
When the baking soda and vinegar are in open air, we see the gas as tiny little air bubbles that cause the mixture to fizz. When the reaction is closed off inside a baggie or bottle with a balloon attached, the gas is not able to escape. Instead it fills up the baggie or balloon. Fascinating, right? My 3 year old thought so.
In the experiments we did, we played around with the amount of vinegar and baking soda a bit, but were not able to make the balloon explode. If we had a bigger bottle, like maybe a 2 liter bottle, it would be fun to try again, though we should probably take the experiment outside in that case.
Recommended Age Range: Preschool, Kindergarten, Elementary
Time Required: ~15 minutes
Difficulty: Easy
Cost: Less than $1 in used supplies
Materials:
- about 2 tablespoons baking soda
- abut 1/2 cup vinegar
- balloon
- empty water bottle (or other similar container with small opening)
Supplies & Tools:
- funnel
- tablespoon
Instructions:
- Use the funnel to add a couple tablespoons of baking soda to a balloon.
- Add about an inch or 2 of vinegar to the bottle.
- Carefully attach the balloon to the bottle without letting the baking soda fall in. Get excited!
- Lift the balloon up so the baking soda falls into the vinegar and watch in amazement as the balloon inflates.
Related Links
Chemistry Activities for Kids
Science Activities for Kids
Learning Activities for Kids
Michelle has a PhD in Engineering from Stanford University and a Bachelor's Degree from the California Institute of Technology. 
This is such a fun classic science experiment, and your photos are fantastic! Have you seen our Halloween adaptation?
I saw that on a Facebook a couple days ago after I scheduled my post. Crazy coincidence! Your self-inflating ghost balloons are so cute and such a great idea!
I did this with my Joey Scout mob just a couple of weeks ago—along with a couple of other activities (volcano, lava lamp and I demonstrated the kid version of elephant toothpaste). The whole day was an absolute hit! (We ran out of time to get play with Red Cabbage Water.)
I’d never heard of elephant toothpaste before. (I just looked it up.) I think my kids would really enjoy all of those experiments!