Color Changing Milk

Optional: Check out this second version by Doctor Mad Science!

Instructions:

• 1. Pour milk in a dinner plate so there is about 1/4 of an inch inside it.

  2. In the center of the plate, add 1 drop from each of the four different food coloring bottles: red, yellow, green and blue, keeping the drops close together.

  3. Put a drop of liquid soap on the end of a cotton swab and TOUCH it to the middle of the milk plate, holding it there for 10-15 seconds.

  4. Add another drop of soap to the swab and try again in different locations.

Discuss

Why does this happen? Dish soap is "bipolar" (nonpolar at one end and polar on the other) and weakens chemical bonds holding proteins and fats in the milk. Soap molecules join with fat molecules in the milk. Milk with more fat content produces more colorful results because there is are more fat molecules to combine with the soap.

Document

1. Take pictures of the different steps in your experiment.

2. Have at least 1 person in your group post photos and 3 or more sentences describing what you did and learned in your experiment to your KidBlog.

Clean Up

• 1. Have 1 person rinse your milk plate in the bathroom sink when you are finished.

  2. Throw away your used cotton swab.

This video provides a partial explanation of why the food coloring, soap and milk change as they do in this experiment. (Thanks @sfryer!)