This week's fun activity... Leaf Chromatography

The Autumn season brings about color changes in many of our plant and tree leaves.    Usually, leaves are green because of the amount of chlorophyll inside them; but at the end of summer the plants stop making chlorophyll.  Without the green color from the chlorophyll, the beautiful reds, oranges, and yellow colors appear!  The colors of our Autumn leaves are a mix of these other colors.  For this week’s activity, we will separate out the colored pigments from an Autumn leaf using chromatography!   Chromatography is a method of separating out parts of a mixture.  The word chromatography translates from Greek to “write in color”, which is exactly what happens!

Materials: Leaves  Wooden Spoon  Cups  Isopropyl Alcohol  Plastic Wrap  White Coffee Filters (cut into 1 inch strips)

Step 1 - Collect Head outside and collect some colorful leaves. Try to pick fresh ones, as dried out leaves will not work as well.  Green leaves are okay, too!   There are hidden colors in green leaves that can be seen with chromatography.

Step 2 – Tear Take a leaf (or a few of the same type) and tear them apart into small pieces.   Place them into a glass or cup.  Repeat with a new glass or cup any other leaves you want to do the chromatography on.   Tip: You can try mixing leaves and colors in one glass as well, to try separating out all the colors!

Step 3 - Pour Add enough isopropyl alcohol to completely cover your crushed leaves.   Repeat for any other cups you have.

Step 4 – Crush Use the end of a wooden spoon to press and crush your leaf pieces.  Continue crushing until the isopropyl alcohol solution is dark with the leaf colors.

Step 5 – Evaporate  Cover your glasses with plastic wrap and let sit out overnight to let the isopropyl alcohol evaporate and the to concentrate the colors.   Alternatively, you can place (heat-resistant) glasses in a hot water bath for about 30 minutes to speed up this process.

Step 6 – Chromatography!  Place one end of a filter paper strip into the concentrated solution at the bottom of your cup.  Keep it straight and fold it over the top rim of your glass to keep it in place.   Now, the solution will travel up the filter paper!  Different colors travel at different speeds, so as the solution moves up the paper, the colors separate.  This should take about an hour or two.   The colors you see on the filter paper are combined together in the leaf to produce the leaf’s color!  Amazing!

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Please continue to watch for our weekly activities...  fun learning for ALL ages!