Bath Bombs are Simple Science

By Sara Thompson

Special to the Enterprise

Bath bombs on display at the Mall of America; Photo by Tony Webster, obtained from Wikimedia Commons

Bath bombs are a popular gift for Mother’s Day and is a fun way to let our moms relax. There are countless shapes, scents, and varieties of these small items, but they all work the same way. They are made with the same basic ingredients to create a chemical reaction in the water to make the famous fizz, and it is all science.

The three basic ingredients of a bath bomb are citric acid, baking soda, and corn starch. All powders are inert while dry but will undergo some drastic changes when exposed to water. Citric acid has a chemical formula of C6H8O7, and will dissolve in water, but while it does so the hydrogen atoms will be released into the solution. Baking soda is also called sodium bicarbonate and has a chemical formula of NaHCO3. Baking soda also dissolves in water, the Na will separate from the rest of the molecule. This is where the fun begins. When the positively charged hydrogen atoms come into contact with the negatively charged bicarbonate molecule they will react. This reaction produces carbon dioxide, which is a gas, and causes the bubbly, fizz we see with bath bombs. All of this happens almost instantaneously when the bomb is placed in the water. To help slow the reaction corn starch is added. The starch will bond with both of the other powders and help slow down their reactions, slowing the dissolving, and making the fizzing last for several minutes instead of only seconds.

Other than the three main ingredients that create the reaction, may add other components to add color, smell, or things for benefits. Many bath bombs are colorful and they get their colors simply by adding dye to the powders. Others have perfumes or oils for a pleasant smell to help with relaxation. Other even include espom salts or other materials that help relax muscles or ease aches while being absorbed by the skin.

No matter how a bath bomb looks or smells, they all still contain those main three ingredients of citric acid, baking soda, and corn starch to make the fun, fizzy reaction we know so well. If you gift your mother a bath bomb for Mother’s Day, let her know that it is simply science, with ingredients you can find at any store.

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