Disappearing Colors Experiment

Let kids see for themselves how bleach works with this easy disappearing colors experiment.

Disappearing Colors Project Materials

• food coloring
• water
• household bleach
• dropper
• glass or jar

Procedure

1. Fill a glass or jar about halfway full with water.
2. Add a few drops of food coloring. Stir the liquid to make it colored.
3. Add drops of bleach until the color starts to disappear. You can stir the contents of the glass if you like. Continue until the color is gone.
4. Add a few drops of another color. What happens? The color doesn't spread out the same way as it did when coloring was added to pure water. It forms swirls, which may disappear if there is enough bleach in the water.

Why It Works

Bleach contains sodium hypochlorite, which is an oxidizer. It oxidizes or reacts with the chromophore or color molecules in food coloring. Although the pigment molecule remains, it's shape changes so that it can't absorb/reflect light the same way, so it loses its color as a result of the chemical reaction.

Safety Information

1. Be careful to avoid spilling bleach on skin or clothes. Rinse any spills immediately with lots of water.
2. Make sure young experimenters don't drink bleach or the contents of the glass. Diluted bleach is not particularly dangerous, but not good for you either!
3. When you are done with the project, it's safe to dump the contents of the glass down the drain and to re-use the washed glass for food.