Balloon Science

I am working on my first science project for 2nd grade. I am using vinegar and baking soda to blow up a balloon. I added a variable doing on in a 16.9 oz bottle and the other in a 10 oz bottle. I thought that the smaller bottle would make the largest balloon; however, the opposite happened. I'm not sure how to explain the scientific fact of why that happened. Can you help me?
- Micah Nicholson (age 8)
Pleasant View, TN, USA

Your guess makes some sense. If there's the same amount of gas made in each case, you'd think that the smaller bottle would force more of the gas into the balloon.

Have you tried repeating the experiment several times, measuring the baking soda and the vinegar very carefully to make sure each bottle has the same amount? Did you make sure that the vinegar and baking soda didn't mix until the balloon was sealed on the bottle? (You can do that by putting the vinegar in the bottle and the baking soda in the balloon., then using some care as you put the balloon on the bottle.) Were you careful to make sure that there were no leaks where the balloons attached to the bottles? Each balloon can be different, so trying several times with different ballons helps make sure that isn't an issue.

Mike W.

(published on 03/30/2014)