Discover: Milk Rainbow

Milk is made mostly of water, but it also contains vitamins, minerals, fats, and proteins. Because milk is mostly water, it has the unique property of having a high surface tension.

You learned about water’s surface tension in the Floating Paper Clips activity. You learned that substances such as dish soap can break the surface tension of a liquid.

Substances such as soap and dye can also react with the fat in the milk.

What effect does soap have on the surface tension of milk?

Material
  • whole milk
  • a flat waterproof plate
  • 4 food colourings
  • liquid dishwashing soap
  • cotton swabs

Notebook

Click here to download the instructions for this activity. Save to your Chemistry Notebook.

  Video

For further instructions on how to complete this activity, watch this video:
Milk Rainbow - Cool Science