Wednesday, November 4, 2009

The Colors of Fall: Leaf Extraction Experiment

Fall is in the air, and that means leaves are EVERYWHERE! For a kid, jumping into a freshly raked pile of leaves is probably the most exciting thing to do with them. However, here's a little activity with leaves that might be almost as much fun, as well as provide some insight into the science behind the changing colors of Autumn.

Leaf Pigment Experiment: (I found this activity here, and it was very easy to follow)

What you will need:
- leaves
- small jars (like baby food jars) or glasses (I used small juice glasses)
- cover for jars or plastic wrap
- rubbing alcohol
- paper coffee filter
- shallow pan
- hot tap water
- plastic knife or spoon

What to do:
The first step is to go outside and find some leaves! We (I did this activity with my four year old son) decided to get a few different colors and sizes. You will need 2-3 leaves of each kind.

Next, cut or rip the leaves into small pieces and place them into the glass or jar. I recommend ripping--this part was a lot of fun for everyone!

Now add enough rubbing alcohol to cover the leaves, take plastic spoon or knives and start to pulverize those leaves. You really want to break down the leaves as much as possible. After this process is complete, loosely cover your glasses and put them into their hot water bath (hot tap water in a shallow pan). But don't wander off! They will need some attention whilst soaking--make sure the water stays warm (replace if necessary) and give 'em a swirl every few minutes. Let the leaves soak for at least half an hour.

While the leaves are soaking, cut the coffee filters into long, thin strips. After the leaves are done with their bath, remove the glasses from the water and uncover. Place a strip in each glass, making sure it touches the alcohol, and gently tape the paper to the side of the glass.

Wait about 30-90 minutes, for the alcohol to evaporate and the color to travel up the filter paper. Here's what our filters looked like when we were done:

The color demarcation wasn't quite as impressive as I was hoping for, but our crude paper chromatography still yielded some interesting results. I didn't really discuss much of the HOW the extraction process worked with my son, but he understood that there were different pigments in the leaves which gave the them their color, and that this activity let us separate out those pigments. I'm glad we used a variety of leaves to see the different colors each sample produced. If we were to do this experiment again, I'd vary the size of leaves and the types of paper as well. Overall, this was a fun and fairly easy Fall activity!

1 comment:

Suzanne said...

Hannah and I just completed this experiement...and it was a lot of fun seeing the colors rise. We used pedals from colorful flowers and leaves as well. We got some nice bands of color! I didn't expect to get a green band from a pink flower...but, there obviously must have been some green pigment in there. Thanks for posting this activity Sharon!