Today’s STEAM activity is disappearing colors. It’s another magical experiment that fascinated my kids. It’s simple to do with just a few ingredients you probably have at home right now.  

Safety Note: this experiment uses liquid bleach. Bleach is toxic and can be harmful if inhaled or ingested, and can cause irritation or burns if it comes into contact with skin or eyes. I recommend an adult demonstrate this experiment, wearing proper PPE (safety glasses and rubber gloves), while kids observe the experiment (they may also wear the PPE, if desired). 

MATERIALS:

  • Small clear cups
  • Water
  • Food coloring
  • Dropper
  • Liquid bleach

PROCEDURE:

  1. Fill the cup about 2/3 full with water.

2. Add food coloring to your cup. We used four cups to try the experiment with four colors: red, blue, green, and yellow. If you are only using one cup, I recommend using yellow food coloring – it disappears the best!

Use 1 to 5 drops of food coloring
We used the droppers to stir the food coloring into the water

3. Fill the dropper with bleach.

4. Squeeze the dropper full of bleach into the cup and watch the colored water change. The color should start to disappear. 

It started green…
…turned to blue green…
…to light blue!

5. If the color doesn’t completely disappear you can try adding a second dropper full of bleach to the cup. 

It started red…
…turned to light red…
…to pale pink!

In our experience, yellow disappeared completely, red lightened to a pale pink, green turned to a light blue, and our blue didn’t change much. 

Before, clockwise from top left: Blue, Yellow, Red, Green
After, clockwise from top left: Blue, Clear, Pale Pink, Light Blue

STEAM CONCEPTS LEARNED:

  • Science: Bleach contains sodium hypochlorite as an active ingredient. This releases chlorine when needed. Chlorine is a powerful oxidizer. This means it can take electrons from other molecules, in this case breaking the bonds that make up the color in the molecules. Once the part of the molecule responsible for color is disrupted, it no longer can absorb visible light.
  • Art: Kids will enjoy observing colors and how they change when they come into contact with bleach. They can pick the colors you use then before the experiment ask them to predict what will happen to the color when you add the bleach after explaining to them how bleach lightens colors. 

This experiment really does seem magical to kids, especially when the color changes or completely disappears right before their eyes. I wouldn’t start your demonstration with blue food coloring, or your kids may be disappointed to see little to no change in that color. 

Do you think your kids would enjoy watching this magical experiment? 

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