Ever wonder why leaves change color in the Fall? This is a colorful science activity that examines the change in pigments of leaves.
You will need:
white cloth or white t-shirt, red, blue, or purple leaves, rubbing alcohol, glass bowl, a pot of hot water, dropper pipets, vinegar, lemon juice, baking soda, ammonia cleaner
Now try this:
Safety: This activity must be performed under adult supervision. Some chemicals used may stain clothing. Never mix any household chemicals together. Wear safety glasses.
1) Tear apart leaves into a glass bowl and cover with rubbing alcohol.
2) Place glass bowl into a pot of hot water and allow to sit for 30 minutes until you start to see a red, blue, or purple color change to the rubbing alcohol. Mashing of the plant material during this time can be helpful.
3) Using dropper pipet deliver dropper amounts of the colored rubbing alcohol solution to the white cloth. Observe the colors spreading with each drop. Make the spots on the white cloth to any size desired.
4) Allow drops to dry slightly to at least dampness
5) Using a clean dropper pipet add dropper amounts of one of any selected liquid: vinegar, lemon juice, baking soda, ammonia cleaner to the colored spots on the cloth and observe the "tie dye" affect with each delivery.
6) Let dry completely. Note: washing the cloth will dull and/or remove some of the colors.
The green color in leaves is due to a pigment called chlorophyll. As the seasons change and the amount of sunlight decreases, the chlorophyll decreases in production causing a decrease in the green in leaves. The colors that leaves start to show are primarily from two other pigments called anthocyanins and carotenoids. Anthocyanins are water soluble pigments that can be extracted with water or alcohol solutions. When the pigment is extracted from the leaves and then placed on a medium like cloth (paper will work too), the colors spread in a process known as chromatagraphy. This is due to the different size molecules of differing colors, the lighter molecules spreading faster on the cloth. Another unique behavior of anthocyanins is their sensitivity to pH changes as observed by color changes. Many solutions in your home vary in pH. The solutions with low pH (high acidity) tend to change anthocyanins redish in color. The solutions with high pH (low acidity) tend to change anthocyanins yellow or green.
For more ideas: www.chemicalkim.com