Bath Time Chemistry: DIY Bath Fizzles
Discovery Place Science
You may have taken a bubble bath or used a bath fizzle, but do you know how and why it works? Bath fizzles do exactly what they sound like: they fizzle on contact with water due to a chemical reaction taking place between different ingredients.
The key ingredients in a bath fizzle are baking soda and citric acid. When baking soda and citric acid are mixed and are then put in water, they undergo a chemical reaction which produces lots of carbon dioxide, which in turn makes the bubbles in the water.
Another main ingredient in a bath fizzle is cornstarch. Changing the amount of cornstarch can affect how fizzy the bath fizzles turn out. So, if taking bubble baths is your idea of scientific experimentation, feel free to test different “formulas” after trying out our recipe!
This is an acid-base reaction, where baking soda is a weak base and citric acid is a weak acid. The cornstarch acts as a "filler" to control the reaction between the baking soda and citric acid.
Tip: For more about acids and bases, check out our fun Kitchen Chemistry activity!
Learning Time: 10-15 minutes
Prep Time: 5-10 minutes
Age Range: 12 and up
- Epsom salt
- Citric acid
- Baking soda
- Oil (coconut or olive oil)
- Essential oil (any blend you like; optional)
- Whisk or fork
- Spray bottle (optional)
*Caution: you can make this with all-natural ingredients but make sure you aren't allergic to anything first before trying out your bath fizzle in the bath!
1. Mix ¼ cup Epsom salt, ½ cup citric acid, 1 cup baking soda, and ½ cup cornstarch together in a medium-size bowl and stir until it's all blended.
2. Add in ¼ cup oil and 20-30 drops of essential oils (if you choose) and whisk together until combined again.
3. Add water to the mixture until the ingredients are held together when squeezed in your hands. Add a little bit of water at a time. You can use a clean spray bottle to easily mist your mixture so it doesn’t get too wet.
4. Shape your bath fizzles by hand or use a mold to get the shape you want. If you are using your hands, scoop and press the mixture into a ball (like a snowball!) until you get the desired size.
5. Allow your bath fizzles to sit for 24 hours or until completely dry.
6. Pop one into your bath water and watch it fizzle!
Tip: If the bath fizzles are very crumbly, they may not have had enough water in them. To fix this, you can remake the bath fizzles but try using a little more water.
- You tested your bath fizzles in hot bath water, but do you think they might behave differently in colder water?
- Do you think that changing different ingredients like the citric acid would change what would happen with the fizzle? How?
- Try using molds to make different shapes. You can use soap-making molds, chocolate molds, ice cube trays or even a muffin tray with liners!
- Try adding natural color to your bath fizzles: use turmeric for golden yellow, Ratanjot for purple, blueberry for blue/purple, spirulina for blue/green or madder root powder for pink.
- Try adding different dried flowers to your mix like rose petals, lavender, etc.