top of page
  • Writer's pictureMelissa

Build Your Own Balloon Pump

Updated: Jul 2, 2021

Try this out for some fizzy fun! If you like it, be sure to check out the erupting lemonade post.

During this activity, vinegar and baking soda combine in a bottle to make carbon dioxide gas. You will trap this gas...and see what happens!


  • 1 glass beverage bottle

  • 1 funnel

  • 1 balloon

  • 1 twist tie

  • ½ tablespoon baking soda

  • ½ cup vinegar


1) Fit the mouth of your balloon over the end of the funnel and add 1/2 tablespoon baking soda to the balloon. Use a twist tie to keep the baking soda from falling out of the balloon too soon. A thin, inexpensive balloon (e.g. dollar store) works best here. If you have a sturdier balloon, I recommend inflating and deflating it once to stretch it out before adding the baking soda.

2) Pour the vinegar into the glass bottle. You can use a funnel for this, or just pour slowly. Can you smell the vinegar as you pour it into the bottle?

3) Keeping the twist tie in place, position the balloon on the neck of the glass bottle. Do your best to center the balloon opening over the top of the bottle, and to make sure the balloon is pulled down a bit over the neck of the bottle rather than perched on top.

4) Hold the glass bottle with one hand and notice how warm or cool the bottle feels. Remove the twist tie, stand the balloon up over the bottle and shake the balloon a bit to encourage all the baking soda to fall into the bottle.

5) What happens inside the bottle? Do you see bubbles? Do you hear fizzing noises? What happened to your balloon? Did it inflate more or less than you expected? How about the bottle - does it feel warmer or colder than when you started?

6) Cleanup - safe to rinse down the drain.


In this activity, you performed a chemical reaction. A chemical reaction happens when two or more different molecules combine to make new molecules.

Here is one way to describe your chemical reaction:

vinegar + baking soda → carbon dioxide + water + sodium acetate

Could you feel the bottle get a bit colder while the reaction was happening? This is an endothermic reaction. What does that mean? The amount of energy absorbed when vinegar and baking soda molecules break apart is greater than the amount of energy released when new bonds are formed to make carbon dioxide. You can tell that the reaction is endothermic because the contents of the bottle get colder as they fizz.

If the chemical reaction went to completion, all the vinegar and baking soda will be converted to new molecules: carbon dioxide gas, water, sodium ions and acetate ions. Can you see any baking soda? If you carefully remove the balloon (once the reaction has stopped bubbling) can you smell any vinegar inside the bottle? Based on your observations, did your chemical reaction proceed to completion?

If you haven't done so already - pinch the neck of the balloon to trap the gas inside, pull it off the bottle and tie a knot. How does the balloon feel? Is it heavier or lighter than you expected? If you have another balloon handy, you can inflate it to about the same size with your own air, and compare the two balloons. Do they feel the same, or does one balloon feel heavier than the other?

While humans exhale around 4 percent carbon dioxide, all the gas produced in the vinegar and baking soda reaction is carbon dioxide. There is some ambient air inside the bottle and the balloon before the reaction starts. Still, a balloon inflated by the chemical reaction-powered balloon pump is enriched for carbon dioxide, relative to a balloon inflated with exhaled air. If you thought the carbon dioxide-filled balloon felt heavier, that is because exhaled air is mostly made up of nitrogen gas and oxygen gas. Carbon dioxide gas is heavier than both of these gases. If you are interested in learning a little more about which molecules are in the air we inhale and exhale, check out this article from

Click below to download a pdf of the Balloon Pump DIY science kit for easier printing.

balloon pump kit
Download PDF • 44KB

Make messes, have fun and spread science joy!

13 views0 comments

Recent Posts

See All


Post: Blog2_Post
bottom of page