Marker Chromatography

Chromatography is a BIG word for young superheroes but this is a super simple experiment that allows for tons of variations and extensions.  All you need are some markers (no sharpies or permanent ones), coffee filters and water!  So coffee addicts, can you spare some of your precious filters for an experiment?  If I can, YOU can!

Here’s what you need to get started:

  • Some jars (clear cups will work too)
  • water
  • Markers in rainbow colors, be sure to include brown and black!
  • Spray bottles and eye droppers (optional)IMG_1939

Cut the filters in half and have the kids make dots with the various markers about 1/2-3/4 inch from the bottom.  We made 4 dots per filter, spacing them out so the colors don’t run into each other.

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We also did one coffee filter with just a black line across the bottom.

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Add about 1/2 inch of water to the jars.  Then carefully place the coffee filter in the jar, wrapping it around the side.  Once it gets wet, it will immediately stick to the side of the jar which makes it easier to see.

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Observe the different colors, patterns from the different markers.  Ask your superheroes why they think that is happening.  I was pleasantly surprised that my 5 year old was able to deduce that the green marker separated into yellow and blue because yellow + blue = green.

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After about 5 minutes, I carefully took the filters out and placed them on a paper towel to dry so we could observe them a little bit better. Notice the primary colors didn’t separate into different colors but the brown is showing green and pink.  The orange shows yellow and some pink, the green shows yellow and blue, the purple shows blue, purple and pink.

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The black line below allowed us to see all the different colors, orange, yellow, green, blue and pink

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While they were drying, my superheroes decided they wanted to draw pictures on a new filter and then spray them water. You can use spray bottles or even eye droppers.  So, of course, we did.  (I think they did something similar at school for an art project and that might be where he got the idea from).  The picture below was drawn with black brown and green and ended up showing brown, orange, green, blue, pink

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And below is my older superhero’s design

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So easy and it only took us about 10 minutes from start to finish.  See, there is ALWAYS time to fit in a bit of science!

The Science behind the Activity:

The coffee filter allows the water-soluble components (those that dissolve in water) of the marker to separate.  When the water in the jar hits the filter, the water molecules travel up the filter through the process of capillary action.  When the water reaches the color, the molecules of pigment in the marker dissolve in water and are carried up the filter with the water.  Depending on the pigments, some will travel faster than others, allowing us to see the the different pigments separately.

Extensions:

This experiment can be done in many different ways.  You can attach the filter to a stick and dip the bottom into water and watch the pigments separate.  You can test different brands of markers to see if there are any differences.  Trying different solvents besides water to see if that affects the separation (rubbing alcohol is a good one to try).  One variation I will try around Halloween is to see how the pigments in colored candy coatings separate!

For older superheroes, set up the experiment in parallel with them but don’t let them see which colors you are using.  Compare your unknown results to those they ran and see if they can guess which colors you used!

Once the pigments separate and the filters are dry, use the pretty filters to make an infinite number of art projects!

Follow this link to see where I got the idea from and more details about the experiment: http://theexplorationstation.wordpress.com/2009/04/14/coffee-filter-chromatography/

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