Have you ever used a bath bomb? They look colorful, smell amazing, and provide you a relaxing bath! In this experiment, we are going to create bath bombs, as well as learn the science behind the magic that occurs when you place it in the bathtub. If you’ve never used a bath bomb, all you have to do is place the bath bomb in hot water in your bathtub. After the bath bomb dissolves, step in your bathtub and enjoy your bath.

*Warning: ingredients in bath bombs can irritate your skin. If you don’t often use bath bombs, please proceed with caution. During the experiment, do not touch your eyes, mouth, or nose. If these areas do become irritated, immediately rinse with cold water.

If you are under 13 years of age, please have a parent or legal guardian help you!

Materials:
1 cup baking soda
½ cup citric acid
½ cup corn starch
1/2 cup sea salt (must be sea salt)
2 tablespoons of water
2 ½ tablespoons of melted coconut oil
Food coloring
2 bowls
Bath bomb molds (or you can use a muffin pan)
1 spoon

Instructions:

Mix the baking soda, citric acid, cornstarch, and salt together in your bowl.
Mix the coconut oil and water together in another bowl. Then, slowly add this mixture to the dry ingredients from Step 1. Mix well until the mixture is like wet sand.
Add some water if the mixture seems too dry.
Now, add a few drops of your chosen food coloring to the mixture. Mix well.
Using your bath bomb mold, fill one side of the bath bomb mold with some of the mixture. For the other side of the mold, add some more mixture. Once both sides are full, firmly press the 2 sides of the mold together.
Let the bath bomb sit with the mold on for 5-10 minutes. Using the spoon, tap the mold. Then, remove the top part of the mold to reveal a spherical-shaped bath bomb. If the bomb breaks apart, add the mold and try this process again.
After the bath bomb shows a spherical shape, remove the entire bomb from the mold. Allow the bath bombs to dry overnight.
When ready to use, just drop the bath bomb into warm water in your bathtub! Once the bath bomb fizzles and dissolves, you can either drain your tub or take a bath!

How does the bath bomb get its shape?

As you can tell, bath bombs have many ingredients! However, the most important players are citric acid and baking soda. When citric acid and baking soda are mixed and placed in warm water, they go through a chemical reaction. The reaction causes the bath bomb to fizz and dissolve in the water. This is called an acid-base reaction, where the baking soda is a weak base and citric acid is a weak acid. The bubbles that make the water fizzy are made of carbon dioxide gas. Another ingredient, cornstarch, acts as a “filler” to control this chemical reaction. If there is too much cornstarch, the bath bomb wouldn’t produce as much of the fizzing effect.

Bath bombs make great gifts to yourself and to others! Hopefully, you were able to see not only the dazzling effect of bath bombs but to also learn the science behind bath bombs!