The Science of the Fizz
At Trades of Brit, we believe every bath bomb is more than a bath product, it's a beautiful blend of chemistry, nature, and self-care.
When a bath bomb is dropped into water, a chemical reaction begins. In its dry state, the ingredients remain stable because the molecules are essentially locked in place and unable to interact. Once placed in water, the water dissolves the ingredients, allowing them to move freely, mix together, and react.
The two key ingredients responsible for the fizz are citric acid (think lemon juice) and sodium bicarbonate (baking soda). As they dissolve, they undergo an acid-base reaction that produces carbon dioxide gas (CO₂), water, and a gentle salt called sodium citrate. The carbon dioxide gas creates the stream of bubbles that gives bath bombs their signature fizz.
The reaction can be represented as:
Baking Soda + Citric Acid → Carbon Dioxide + Water + Sodium Citrate
NaHCO₃ + C₆H₈O₇ → CO₂ + H₂O + Na₃C₆H₅O₇
Where:
- NaHCO₃ = Sodium Bicarbonate (Baking Soda) - Base
- C₆H₈O₇ = Citric Acid - Acid
- CO₂ = Carbon Dioxide (the fizzing bubbles) - Gas
- H₂O = Water
- Na₃C₆H₅O₇ = Sodium Citrate - Salt
Interesting aspect of bath bomb chemistry is that the reaction is endothermic, meaning it absorbs a small amount of heat from the surrounding water. As the bath bomb dissolves, you may notice the water feels ever so slightly cooler. This occurs because energy is being absorbed as the reaction proceeds.
What appears to be a simple fizzy bath experience is actually a wonderful demonstration of chemistry in action. It's a reminder that science isn't confined to laboratories, it can be found in everyday moments, transforming a bath into an experience that is both relaxing and educational.
At Trades of Brit, we love uncovering the science behind natural body care because understanding how ingredients work allows us to appreciate the remarkable chemistry happening all around us.
Ingredients (150g Total)
- Baking Soda: 65g (1/3 cup)
- Citric Acid: 30g (1/4 cup)
- Epsom Salt: 35g (2.5 tablespoons))
- Cornstarch: 20g (1.5 tablespoons)
- Melted Coconut Oil: 10g (2 1/4 teaspoons)
- Essential or Fragrance Oil: 4–6 drops
- Witch Hazel: 1-2 spritzes
Bath Bomb Assembly Instructions
- Carefully pour the dry ingredients into a plastic cup.
- Slowly drizzle the oil mixture into the dry ingredients, adding just a few drops at a time.
- Stir quickly and thoroughly to prevent the mixture from fizzing.
- Separate your bath bomb mold into two halves. Firmly pack each half with the bath bomb mixture.
- If the mixture feels too dry and does not hold its shape when squeezed, spritz it once with witch hazel. The mixture should feel like damp sand.
- Continue adding and packing the mixture into both halves of the mold until they are completely full and tightly packed.
- Press the two halves of the mold together firmly.
- Allow your bath bomb to dry and harden in the mold for at least 24 hours.
- Once your bath bomb is ready, it's bath time! Drop your bath bomb into a warm bath and watch it fizz.
Important
- Adult supervision is recommended.
- For external use only.
- Do not eat the ingredients.
- Avoid contact with eyes.
