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Friday, July 2, 2010

Blow up a Balloon with Chemistry

Chemicals come in three familiar forms: solids, liquids and gasses. Sometimes when two chemicals mix together they interact to form an entirely new chemical: we call this a chemical reaction. In Experiment 1 kid scientists can perform their own chemical reaction to form a gas from a solid and a liquid. 

Living organisms are essentially chemical factories. In experiment 2 kids utilize yeast digestion to blow up a balloon.

Ages 6 and up; Download Printable PDF

EXPERIMENT 1: Blow up a balloon with chemistry

You will need:
measuring cup
small necked bottle
baking soda
white vinegar

Secure the neck of the balloon over the tip of the funnel, then pour ~2 tablespoons of baking soda through the funnel into the balloon; remove funnel.  Pour ~1 cup of vinegar into the bottle. Taking care not to let any baking soda enter the bottle, secure the neck of the balloon over the neck of the bottle.

Grip the neck of the balloon to secure it onto the bottle, then lift the body of the balloon and shake to pour the baking soda into the bottle. Watch the balloon inflate. Note: This can be messy. Do outdoors. 

More You Can Try

Erupting volcanos 
Pour ~1/4 cup baking soda into a narrow neck bottle.  If you’ve got a sandbox available, bury the bottle in the sand up to its neck; this is your volcano. In a measuring cup, add a couple of drops of food coloring to ~1/2 cup of vinegar. Pour the vinegar into your volcano and watch it erupt. 

Baking soda-free cupcake 
Prepare a homemade cupcake recipe but don’t add the baking soda or baking powder.  Make one cupcake and insert a toothpick into the batter (so you know that this cupcake doesn’t contain baking soda/powder), then add the baking soda/powder to the remaining batter.  Make the remaining cupcakes and bake as directed.  Cut one regular cupcake and one soda-less cupcake in half. Did the baking soda/powder-less cupcake turn out differently than the others? If so, why do you think this is true?

What’s Happening?

The simple explanation: When baking soda and vinegar are mixed together, they undergo a chemical reaction to create an altogether new chemical, carbon dioxide gas, which fills the balloon and causes it to inflate. The same reaction causes the baking soda volcano to erupt.

Baking soda is commonly used to add air bubbles (actually carbon dioxide bubbles) to baked goods such as cakes and cookies. The air bubbles give the baked goods a light, airy texture.

The hard-core chemical explanation: Baking soda is sodium carbonate (NaHCO3) and vinegar is acetic acid (CH3COOH). In water, acetic acid breaks down into CH3COO- and H+. The H+ reacts with the NaHCO3 to make carbon dioxide:

 NaHCO3 + H+ –> Na+ + CO2 + H2O

EXPERIMENT 2: Can yeast blow up a balloon?

You will need:
a funnel
a balloon

Instructions Secure a funnel onto the neck of a balloon. Pour ~1 Tbsp of sugar, ~1 tsp of yeast and ~2 Tbsp water into the balloon. Tie the balloon and observe it over the course of several hours. 

What's Happening?
The yeast digests the sugar and produces carbon dioxide gas, causing the balloon to inflate. Humans also produce carbon dioxide gas when we digest food, which we exhale when we breath out. Bakers add yeast to bread to make it rise.

Did you know?
• Many recipes that require baking soda also require an acid, such as lemon juice or vinegar.  Why do you think this is true?

• Baking powder is another chemical commonly added to baked goods to give them a light, airy texture. Baking powder is actually a mixture of baking soda and acidic powders that react in water to make carbon dioxide gas. Most modern baking powder is “Double Acting”. This means it contains two acidic powders: one that reacts at room temperature, and one that reacts at the higher temperatures used during baking.


  1. hmmm nice im doing this experiment for a science project

  2. This is great keep doing what you're doing this is amazing scrumpdiliumptios{that means amazingly great}

    you guys are really great