Incredible Chemical Spectacles

Fizzy Bath Bombs

When acids and bases come into contact with one another, a chemical reaction occurs. Follow the instructions below to make a fun bath-time chemical reaction with a Fizzy Bath Bomb.

Acids and bases are substances that break down into ions (charged atoms) and other compounds when placed in water. Acids break down into hydrogen ions (H+) and bases break down into hydroxide ions (OH-). Many acids taste and smell sour (like vinegar). Bases often have a bitter, soapy taste (like baking soda). NEVER taste a chemical! If you want to know if something is an acid or a base, you can look on the label, ask an adult, research it on the Internet, or test it with cabbage juice (see the Invisible Ink experiment for details).

Did you know?

Fizzy Bath Bombs are great homemade presents! Wrap them up and give them to family and friends.


  • 2 tbsp. (30 mL) citric acid
  • 2 tbsp. (30 mL) cornstarch
  • ¼ cup (60 mL) baking soda
  • 1/8 tsp. (0.6 mL) fragrance oil (optional)
  • 2 tbsp. (30 mL) vegetable oil or baby oil
  • 2 mixing bowls
  • waxed paper

Let's Get Started

  1. Mix the citric acid, cornstarch and baking soda together in a bowl.
  2. In another bowl, mix the oil and fragrance.
  3. Slowly incorporate the oil into the dry ingredients. Mix well. The paste should hold together when squeezed. If the mixture is too liquid, add baking soda. If the mixture is too dry, add a bit more oil.
  4. Make small shapes the size of ping-pong balls with the mixture.
  5. Store bath bombs in a sealed container, away from moisture.
  6. Add one to your bath and enjoy!

What Happened? Let's Check the Results

The citric acid (an acid) and the baking soda (a base) will react and produce carbon dioxide gas, which is what makes it fizz. A reaction between an acid and a base is called a "neutralization reaction". This type of reaction happens only in water, where the ions from the acid and the base are free to react.

Take Note!

Try the Invisible Ink experiment to learn more about acids and bases.

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