You can learn a lot about something by pulling it apart. But in this case we’re going to pull something different apart – colors! Did you know you can even separate those?
In this lesson we will
- Practice chromatography
- Play with some marker colors
- See what colors are really going on INSDIE a leaf!
Time to Complete
2 hours wait time, 30+ minute lesson
Chromatography, polarity, chlorophyll
- Bowl or food storage container – 1
- Paper clips – 5-10
- Paper towel – 2
- 91% Isopropyl alcohol or rubbing alcohol – 1 cup
- Leaves of different species & colors – 4 or 5
- Cups or jars – 4 or 5
- Color Analysis Sheet – 1 per child
Choose markers off all different colors and brands. Start off with at least 4 or 5 but you can really repeat with as many markers and you like. Just have fun!
- Cut the leaves into small pieces, keeping them separate
- Grind them one at a time with a mortar & pestle or smash them in a cup using the back of a spoon.
- Place them each in separate cups or jars and add 2 Tablespoons of isopropyl alcohol to each.
We let these sit for about 2 hours so you should start this first. Kids can help with this since we’re not going for perfection.
In this example photo, we have used a fresh green oak leaf, a fresh green primrose leaf, and pressed yellow and red leaf.
You know, you can learn a lot about things by pulling them apart. Something like a clock has gears and motors that we can’t usually see to keep it running. But did you know you can put things apart that do not even look like they have different parts?
Well lets do just that! We’re going to take 2 different things that do not look like they can even be taken apart (marker ink and leaves) and see what we find.
This method is called chromatography. We use alcohol to pull apart the different components. A marker may look black, but it is actually a mixture of colors. Plus, each company makes their ink a little differently so even samples that look the same color will actually be unique. Read more about chromatography in “The Science” section.
Let’s prepare our markers for examination! Prepare a sample of each marker in this same way.
- Cut a strip of paper towel about 1 inch (2.5 cm) wide and several inches long. It needs to be long enough to reach from the bottom of your bowl or food storage container to the top and be paperclipped to the edge.
- Draw a wide band of color across the strip of paper towel about 1 inch (2.5 cm) from the bottom.
- Fill the bottom of your bowl or food storage container with about 1/8 inch (3 mm) of alcohol.
- Paper clip the prepared sample strips to the side of the bowl with just the end of the sample touching the alcohol. DO NOT LET THE MARKER INK DIRECTLY TOUCH THE ALCOHOL. It will ruin the sample. The alcohol needs to climb slowly up the paper towel.
Now you’ll have to be patient and do a little waiting. The samples need at least 15 minutes to start separating but you will be better bands of color if you leave them for at least an hour. In the end, you will get something that looks like this.
Record your observations and notes on the Color Analysis Sheet.
Dry erase markers don’t really separate as well as other kinds from our experiment. Repeat this as many times as you would like to see what you can find.
This process works great on markers but how about something else? We are now going to perform the same chromatography on leaves.
This experiment is a little different than with the markers. The marker ink is has the colors all ready to be separated but the leaves have the color locked away inside. That is why we chopped them, smashed them, and covered them with alcohol. The alcohol will help pull out the colors and then we can test them.
- Cut out a 1 inch (2.5 cm) wide strip of paper towel just like for the marker experiment. Make sure it will reach all the way to the bottom of the glass or jar with the leaf/alcohol mixture.
- Set 1 paper towel strip in each jar or glass and paper clip it to the top so it does not slip.
- Allow the paper towel to soak for at least 1 hour.
- Remove the paper towel strip and examine your samples. They should look something like this with 4 separate color bands. Read more about each color in “The Science” section.
Record your observation and notes on the Color Analysis Sheet.
Take a look at real life
This is all very fun but how does it help us in real life? Can you think of any ways this might help?
Chromatography is one of THE most used analysis methods. People use it every day for testing water, product quality control, separating DNA, etc.
Want more details on why chromatography works the way it does? Remember to check out “The Science” section.
There so much extra on the PDF!
Our lesson plan PDF is just chock full of good stuff that is too much to put here. Grab the full lesson plan to get “The Science” section, vocabulary, and the Color Analysis sheet.
This activity is part of Who Stole the Cake? [Unit 2]. Jump over to the unit main page to see all lessons and activities.