Why do leaves change colors?

Recently we did a science experiment with the kids.  We were talking about leaves and why they change colors.  In the Spring and Summer they are various shades of green, but once the cold weather of Fall hits the leaves start changing colors.

What is chromatography?  The definition of chromatography is the separation of mixtures into their constituents by preferential adsorption by a solid, as a column of silica (column chromatography) or a strip of filter paper (paper chromatography) or by a gel.  We decided to uncover the rainbow of colors found in each leaf.  The kids picked 9 leaves to experiment.

 Science Experiment Items:

• Leaves (different colors and types)
• White Coffee Filters
• Rubbing Alcohol
• Scissors

The leaves contain a green pigment, chlorophyll.  Chlorophyll is used to capture sunlight.  By using chromatography you will be able to see the different colors present in the leaves.

Collect a variety of leaves to test.  Pour 1/4 inch of rubbing alcohol into the bottom of a jar.  Cut the leaves into small pieces and put each leaf into its own container.  Cut the coffee filter into 1 inch strips.  Put a strip of coffee filter in each container (the bottom of the strip should touch the rubbing alcohol) and you can fold the top of the strip over the top of the container.

Watch carefully as the rubbing alcohol moves up the coffee filter paper.  You will notice the colors moving up the paper as well.    It takes about 15 to 20 minutes for the rubbing to move up the paper.

We did the experiment saw the results and then “just for fun” we left it overnight to see what would happen.

One of the girls picked out 2 dark green leaves and one flower petal to test in this experiment.  I figured they might as well see what happens with it too!

One of the girls picked out a red, yellow, and orange leaf to experiment with today!

Check out the cool colors!

What one of the leaves looked after sitting over night; after the rubbing alcohol evaporated.

As you can see the red flower petals (in the container on the left) did not amount to much color on the paper.  The other two leaves did great!

Some cool colors found in these leaves.

Our 9 different leaf experiments and the colors we found inside them.  We found the most variety of colors in the dark green leaves.  The lighter colors on the left were ones that were turning colors (yellow, orange, and red leaves).    The one on the right that looks almost white with a very faint yellow color is the red flower petal.  Glad I let the kids experiment with that too even though it wasn’t a leaf, it was still a good learning lesson.