Thursday, October 10, 2013

SET: Why Leaves Change Color

This experiment was so tempting to do considering the time of the year.  However, ours took a long time to actually see any results, so try to follow the experiment as closely as possible.  You could also start it in the morning and then, by evening, the results should be visible.

You will need:
-Leaves of different colors
-Clear glasses or jars
-Rubbing Alcohol
-Coffee Filters
-Aluminum Foil or plastic baggie
-A large Tupperware or Pyrex that will hold the glasses

We had a fun time collecting our different color leaves:

Then we sorted the leaves by color and the monkeys got started on tearing up our leaves and crushing them up into our glasses:

Once the leaves are crushed up finely, pour rubbing alcohol into the glasses until it completely covers the leaves.  *Remember to have an adult do this with the younger ones and be sure to do this in a well-ventilated area*.

Continue to mash up the leaves until the rubbing alcohol starts changing colors.  The rubbing alcohol turning a different color will ensure the experiment's success, so really focus on mashing up those leaves!  This was the step we didn't quite do as well and it's possible that's why our results took longer to see.

When finished, cover the glasses with aluminum foil.  You will then place the glasses in the Pyrex or Tupperware container and fill up the container with about an inch of hot water (again, have an adult do this if working with younger children).

The next step is to wait for 30 minutes while periodically agitating the leaves and refilling the water to make sure the water stays warm.  We made ourselves busy with spraying colored water on some of our coffee filters:

After about 40 minutes, we removed the aluminum foil and tore our coffee filters into strips.  We placed the filters into the glasses and then taped the filter to the edge of the glass so it would stay in place:

And we waited again.  This time for a good hour, but we didn't see any results :(

The next morning, however, we saw the colors creeping up the coffee filters:

The longer we left it, the more colors we saw emerge:

After 48 hours, the coffee filters had amazing colorful patterns on them!

So, how does it work?

It's rather complicated, but here's a simpler version.  In the spring and summer, the leaves are green because of the chlorophyll.  The other colors you see on the filter are always there inside the leaf, but chlorophyll is so dominant it hides the other colors.  In the fall, however, the chlorophyll breaks down, which allows the other colors to be seen.  By using the heat and the rubbing alcohol, you are essentially using the technique of chromatography to separate the pigments.  Science can be so colorful!

What's been your favorite science experiment so far?

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