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 – chemically 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
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:
ACID + ALKALI = WATER = CARBON DIOXIDE (FIZZ)