Cup of milk
Liquid dish soap
Cotton swabs/Q tips
Pour enough milk to cover the bottom of the plate with a depth of ¼ in.
Add one drop each of different colored food coloring close to the center of the milk and close to each other.
Touch one end of a clean cotton swab to the center of the milk. What happens?
Dip the other end of the cotton swab in dish soap, then in the center of the milk. What happens this time?
Try placing the cotton swab in different places in the milk. What happens when you remove the swab?
Milk is mostly water, but it also contains vitamins, minerals, proteins, and tiny droplets of fat suspended in solution. Fats and proteins are sensitive to changes in the surrounding solution (the milk). The secret of the bursting colors is the chemistry of that tiny drop of soap. Inside that tiny drop soap molecule is bipolar, so the water-loving (hydrophilic) end of it dissolves in water while the water-fearing (hydrophobic) end of it attaches to the fat globule in the milk.
Taking it further
Try the same experiment with different liquids like water, vinegar, nonfat milk, etc. to see if you get the same explosion of color!
Inspired by Steve Spangler Science
Special thanks to Honor Pimentel and Yaiza Fernandez for the Spanish translation
Create a public service announcement for your family and friends about the importance of washing your hands with soap! Your PSA can be in the form of a poster or short video. We have provided a poster example and template here, but feel free to use your creativity!
We will select one lucky kid at the end of the week to win a free Curieus swag bag with a Curieus shirt, stickers, and candy. Submit your PSA to firstname.lastname@example.org by 8 pm on Friday, May 8th!