Fizzy Science Behind Bath Bombs

Recently one of my children has been asking for bath bombs, which, until he asked for it, was not something I had ever bought. Bath time in our house tends to be less of the relaxing, soaking in a warm, fizzy bath moment and more of a ‘STOP SPLASHING OUT OF THE TUB!’ kind of adventure. But nonetheless, the bath bomb request came in, and the next time I was in the store, I went to look for bath bombs. FYI: those things are expensive.

So, what is a scientist mother to do? The choice was clear. It was time to embark on a make your own bath bomb adventure.

First, what are bath bombs? Balls of stuff that explode into a fizzy, sometimes colorful, reportedly soothing thing when put into water. We need two main components to make a good bath bomb: the stuff that fizzes and the stuff that soothes/cleans/etc.

What fizzes? Usually a gas, and for the most part in commercial products, that gas is carbon dioxide and it is formed from the reaction of baking soda with something else that causes it to release its CO2 gas. There are other options for fizzy things too, but most of them are less safe than a CO2 gas release. Most DIY bath bombs use baking soda and citric acid in combination, which react to release carbon dioxide gas only when it gets wet.

What soothes? Essential oils, maybe. Feel free to add some of that (only a little bit, those are powerful smelling things). Other soapy stuff. Maybe Epsom salts. This is not really the scientific part, to be honest, so add whatever you want.

What else? Usually bath bombs with add another powder ingredient, like corn starch, which will help clump everything together and enable it to holds its shape until the bomb ends up in the bath.

There are lots of instructions available online, including options for making edible bath bombs. Check out some of them here:; here:; and here:

Happy bombing of baths, readers! Enjoy!

#science #summer #experiment

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