Carbon dioxide produces fizzy bubbles in bath bombs, istockphoto, used with permission
Carbon dioxide produces fizzy bubbles in bath bombs, istockphoto, used with permission

As any trained and certified aromatherapist knows, when you study essential oils, you study chemistry too. The different chemical components that go into making an essential oil, derived from its plant source, are what give a specific essential oil its therapeutic properties. However, if you are considering making your own aromatherapy products, you will also run across other chemical reactions between ingredients, in order to make them react the way they do.

Today’s question is: Why does a bath bomb fizz?

The Ingredients of a Bath Bomb

A basic bath bomb is made up of just a few ingredients; these include the following ingredients, the first two of which are important to making sure a bath bomb fizzes:

  • citric acid – a weak organic acid.  Citric acid is a white crystalline powder which is often used as a natural preservative in cosmetic products.  It can also be used to adjust the pH level and prevent natural cosmetic products from becoming too alkaline. Citrus fruits, such as lemons, limes and oranges, contain high levels of citric acid

  • bicarbonate of soda – chemicallly known as sodium bicarbonate and also by the common name of baking soda. The natural mineral form of sodium bicarbonate is nahcolite; it is often found dissolved in mineral springs.  Bicarbonate of soda os a white, crystalline solid but appears as a white, fine powder for cosmetic and culinary purposes.  You can use it in natural cosmetic products to smooth the skin, clean and as a deodorant.  It is also used in baking recipes and as an antacid for indigestion and heartburn (when mixed with water)

  • powdered ingredients such as cornstarch and bath salts

  • essential oils

  • carrier oils

  • coloring

  • water

  • butters.

The Chemical Reaction of a Bath Bomb

When you add a bath bomb to water, it starts to fizz; the reason that it does this is chemistry.  Bath bombs are made up of several ingredients but, in simplistic terms, there are three ingredients that cause this specific chemical reaction.

Combine citric acid together with bicarbonate of soda and the dry ingredients will not cause a chemical reaction.  However, add in water, and the mixture starts to produce carbon dioxide bubbles (which produces the fizz in bath bombs).  In simple chemistry terms this means:


Learn to Make Your Own Bath Bombs and Bath Products

If you would like to make your own aromatherapy products, check out the Sedona Aromatherapie courses home page and learn to make aromatherapy butters, balms, creams, lotions, perfumes and more. The information contained within this post is part of a more comprehensive course on making Basic Bath Products with Essential Oils which is now available.

Have fun!

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One Thought on “Why Does a Bath Bomb Fizz?”

  • This is a wonderful informative way to learn all about aromatherapy, and the chemistry behind making wonderful products to use for baths, & on your body. Not only do you explain what goes into the products, but how their used, and the part they play in making each product unique, and therapeutic. I got all the information I needed from this one site, that I didn’t have to search others! With so many fun and exciting things to learn and make yourself body essentials, I know I’ll be coming back to to try attempt making my own body therapy essentials. So thank you for providing such important, and needed information, I learned some interesting things, and want to try some too.

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