Friday, October 5, 2012

Autumn Leaf Chromatography

The leaves around here's are just now really starting to show some color, and many of the trees are still entirely green.  I found this leaf chromatography experiment (from Almost Unschoolers) that predicted what color leaves would turn. I decided to try it with the girls.  It was a bit advanced for them, but they at least had a fun time collecting and tearing up the leaves. They did think the colors were cool too even if they didn't care about the fact that they could predict the future color of the trees.

Obviously the first step is to collect a variety of leaves: green, red, and yellow.  I tried to get a few sets from the same tree, so we had one green leaf and one that had already changed. We used a red maple leaf and a green leaf from the same tree, a maple leaf from another tree, a yellow mystery leaf that I think is from an elm  , a green one from the same tree, a dark green leaf from a mystery tree, a redbud leaf, a pear leaf, and what I think is a walnut leaf.

Then we torn up the leaves in some clear glasses.

We added enough rubbing alcohol to cover the leaves and waited.  It seemed like we had to wait a couple hours for the colors to really show.  I think part of it may be that we picked the leaves the day before, and they had dried out some.

After sitting for a couple hours most of the colors were apparent in the glasses.  At this point we added strips of coffee filter to each glass.  

We allowed those to sit for 3-4 hours, and pulled out the. coffee filter strips on e it looked like they had stopped absorbing the rubbing alcohol.  On the filters we observed bands of color.  There was at least a band of color which was the me as the color the leaf appeared when we started.  Most of them also had a second band.  For the green leaves the second band of color was what they would most likely turn as the weather cooled.

My walnut leaf had a yellowish brown band as well as a green band, the redbud had a yellow band as well as a green one, and the pear leaf had a brown band as well as a dark green one.

These were my elm? leaves.  One has a yellow line as it had already turned; while the other has a yellowish green line int he same spot.  They both have the brown line at the top.

These are my maple leaves.  The red one had a dark brownish band at the top ; while the green one had the same brownish band as well as green bands at the bottom.
From this experiment it looked as if most of our leaves we re going to turn some shade of brown.  We did have a couple yellow or yellow with brown, but even the red didn't give a really clear red.  Again it may have been because the leaves were dry as the red leaf didn't give much color at all (very surprising).  You could appreciate how the green leaves did have other colors hiding in them that showed up in the filter though.

I tried to explain to the girls that the green leaves were producing chlorophyll which is green, but as the weather cooled of they would stop and any other colors in the leaves would be seen.  By this point they had lost interest (such short attention spans), but maybe the idea will stick.  Once they are older I am sure they will enjoy it more.