Blow up a Balloon with Baking Soda and Vinegar

Learn how to blow up a balloon with baking soda and vinegar!

Kids will love this classic science experiment. This acid/base chemical reaction is fun to watch as it bubbles, but it’s even more impressive when you harness the CO₂ produced by the reaction to blow up a balloon.

Recommended Ages: 1st grade through high school!

Young kids will enjoy watching the baking soda and vinegar react and the balloon inflate. You can explain to them that this is a chemical reaction, although they won’t completely understand what that means. Middle schoolers and high schoolers will still think this is fun, and they will be able to understand the acid/base reaction and the chemical formula.

This post was originally published in November 2011 and updated in February 2025.

Supplies Needed for Blowing Up a Balloon with Baking Soda and Vinegar:

• Empty water bottle – we used a 16.9 oz bottle
• Vinegar
• Baking soda
• Funnel

First, use a funnel to pour a spoonful of baking soda into the balloon.

Then pour some vinegar into the bottle. We didn’t measure, but it was about 3 oz.

Stretch the balloon over the mouth of the bottle, and make sure that the baking soda doesn’t dump into the bottle… yet. It helps if you stretch the balloon over the lip that sticks out on the bottle.

**Don’t add more than about 3 oz of vinegar to the bottle, and don’t use more than a spoonful of baking soda. The reaction will be too big, and you’ll end up with liquid in your balloon. It’s best if the balloon contains only CO₂ after the reaction. I’ll explain why in a minute!

Lift up the balloon and dump the baking soda into the vinegar.

The reaction will happen quickly, and the balloon will inflate!

You may need to hang onto the bottle while the reaction is happening so that it doesn’t tip over.

Sooooo cool!!!

The Science Explanation:

Basically, mixing vinegar and baking soda is a simple acid + base reaction. 

Here’s the chemical formula, if you’re interested:

acetic acid (vinegar) + sodium bicarbonate (baking soda) = carbon dioxide + water + sodium acetate (a salt)

CH₃COOH + NaHCO₃ => H₂O + NaOCOCH₃ + CO₂

The carbon dioxide gas expands and takes up more space than the baking soda and vinegar did (the reactants). So the gas has nowhere to go except to expand into the balloon, causing it to inflate.

Because the balloon is filled with CO₂, it falls faster than a normal balloon because it is more dense than room air (which is mostly nitrogen with oxygen and carbon dioxide).  We tied off the balloon from our reaction, and then compared it with a balloon that we blew up to the same size, and it was interesting to see the difference! The CO₂ balloon falls like a rock!

If you use too much baking soda and vinegar, you’ll end up with liquid in the balloon, which will make it MUCH heavier than a regular balloon. Ideally, you want the balloon to be filled with ONLY carbon dioxide.

Need more science experiment ideas?

Here are 45+ Simple Science Experiments for Kids!