Make Foam Rainbows at Home

Materials you'll need

• 6 colorful paper cups
• 1 tbsp egg whites per cup (6 tbsp total)
• Food coloring (one color per cup)
• 1 tbsp baking soda per cup
• 1/4 cup vinegar per cup

 

Step-by-step tutorial

Step 1: Set out your colorful paper cups in a row — one for each color of the rainbow!

Step 2: Add 1 tablespoon of egg whites to each cup, then drop in a few drops of food coloring. Use a different color for each cup to make your rainbow.

Step 3: Add 1 tablespoon of baking soda to each cup and stir everything together until well mixed.

Step 4: Pour 1/4 cup of vinegar into each cup and step back because colorful foam will erupt right over the tops of the cups!

Step 5: Watch your rainbow of foamy blobs grow! Once all the cups are overflowing, arrange them together for the full rainbow effect.

Learn more

This experiment is a chemical reaction in disguise! When vinegar (an acid) meets baking soda (a base), they react and produce carbon dioxide — the same gas in fizzy drinks. Normally those gas bubbles pop almost instantly, but egg whites are about 10% protein, and those proteins act like tiny nets that surround each bubble and hold it in place. The result? A thick, long-lasting foam that keeps its shape long after the bubbling stops. The food coloring is just along for the ride, giving each foam its brilliant color!