Last week our annual marker chromatography experiment didn’t go as usual. I’m blaming the new fancier (read more expensive) brand of markers we used. Instead of separating, the colors simply spread. It looked pretty and judging from my kids’ excitement not altogether disappointing, but I started to wonder what other chromatography experiments can we do at home. It had to be something simple that kids could have fun with, while learning about this interesting scientific concept. I am happy to report that there is no end of simple chromatography experiments you can do with kids at home. We tried chromatography experiments with food coloring, candy sprinkles, essential oils, and two types of markers.
The history of Chromatography
Chromatography, or “color writing” from the Greek chroma “color” and graph “to write” is the science of separating mixtures. We also often refer to it simple as Tsvet’s science, after the Russian scientist who discovered the technique and coined the term “chromatography.” Mikhail Tsvet (by the way, I can see why he was drawn to the science of color as his last name “tsvet” is actually a Russian word for “color”) discovered that since different color pigments are carried along at a different speed, they end up in different places. So one can use different substances (gas or liquid) to carry the color and by examining where different colors ended, one can figure out what was combined to make it. Chromatography is now widely used in biochemistry to figure out the ingredients that make up a particular scent and flavor, and is used to detect traces of drugs in urine or traces of pollutants in drinking water. Too bad that Tsvet’s work was largely unknown due to it being in Russian language until years after his death. Today his gravestone carries an inscription: “He was given the discovery of Chromatography: separating molecules, uniting people.”
What is Chromatography
To make it easier for kids to grasp the concept of chromatography, I used a trick I learned from our Waldorf curriculum – storytelling. I started by asking my kids to imagine themselves in a forest. Everywhere they look there are tall and short trees stretching toward the sky like towers. The twigs crunch under their feet. Small animals scatter around in the underbrush. And now magically a toy box drops down from the sky in front of them. In a box there are light things like balls, dolls and books. And heavy toys like Bruder trucks, giant Barbie house, and LEGO table. Suddenly a small flood sweeps through the forest. You are ok because you climbed the trees, but the content of the box is scattered all over the forest floor. Would all toys travel the same way? Would it be as easy for water to sweep the LEGO table through the forest as a beach ball? Probably not! Would someone be able to make some predictions regarding how heavy different toys are by examining how far they travelled? Chromatography is a science that studies the components of a mixture (toys in a toy box). Usually there is a mixture in one state of matter (gas or liquid) that passes through something in another state of matter (liquid or solid) and as it moves the different components of a mixture travel at different rates, thus separating the mixture out. I like chromatography because it’s easy to do at home. Plus each chromatography experiment here is a simple activity in which art and science come together.
Chromatography experiment with Markers
Markers in a variety of colors
Glasses with water
What to do
- Cut paper towels into long stripes, about an inch wide.
- Draw a heavy line with a marker near the top of one stripe (black is usually very exciting color).
- Hang the paper strip over the edge of the glass of water so that the paper towel touches the water, but the line is above the water.
Watch the color spread as the water travels up the paper. The most amazing thing is when colors separate into many different colors. Expect black to spread at least into blue, green, and yellow.
Another fun thing to do is to draw a circle inside the coffee filter and stick it in the cup. It makes an amazing pattern, but we don’t drink coffee, so coffee filters are hard to find in our house.
Note: If you are looking for a creative way to use the strips, you can put them in a blender equipped with a S-blade, add a little water and turn it into a mush. If you press the resulting mush into a cookie cutter and let it dry over night, you end up with a beautiful 3D art. Read about our red heart for inspiration here.
Chromatography Experiment with Candy Sprinkles
paper towels (or coffee filters)
sprinkles of different colors
What to do
- Place sprinkles in the middle of paper towel
- Add water
We knew that yellow and blue is usually made up of just one die, so we didn’t expect much color separation. But we were very surprised to see so much yellow in the red because red is usually just one die too. Of course, my kids couldn’t resist adding a sensory element to the experiment and rubbing the mixture with their fingers.
Another fun thing to do is to try the same experiment with jelly beans and M&Ms.
Chromatography Experiment with Food Coloring
What you need
Food coloring in various colors
Sticks, popsicle sticks, or pencils
What to do
- Cut paper towel in several strips just a bit taller than your cup.
- Add food coloring to an inch of water in a cup.
- Tape the strip to the stick, so that the bottom touches the liquid in the cup.
- Suspend the strips in the cups, so that the the bottom touches the food coloring
Does the color separate into different colors as it creeps up? It was interesting to see so much green coming out of black color.
It’s even more fun to mix many different colors of food coloring in one glass and see how they separate as they move up the paper towel strip. Just don’t add too much black because the strip gets too dark to detect any color separation.
Chromatography Experiment with Essential Oils
If you were ever interested in buying essential oils, the number one question that most probably popped into your head was How can I trust that this essential oil is pure? There are many different ways to check the quality of the essential oils in a laboratory setting, but what about an average home? So far I discovered only one method that is considered “fairly accurate” for testing essential oils at home.
What you need
What to do
- Cut white paper into a strip
- Dispense a drop of essential oil on a paper strip.
- Allow to dry for 24 hours (might take 48 hours for thick oils like Sandalwood).
A pure essential oil should dry without leaving a stain. Essential oil that has been adulterated with synthetic fragrance oil will leave an oily residue on a piece of paper. From ten oils we tested, only 2 failed the test. As you can see on a pic above all the Kis oils passed the test. But my favorite rose oil didn’t pass the test, and neither did Sweet Orange from Aura Cacia (but Sweet Orange from Kis was fine). The fun part of this experiment is that while we were testing all my different oils our house smelled like an Essential Oils Shop.
Chromatography Experiment with Permanent Markers
Since permanent markers are water insoluble (that’s what makes them permanent) we had to use something else. We looked around the house and found rubbing alcohol, nail polish remover and vinegar.
What you need
paper towel strips
permanent markers (black and green were most interesting)
rubbing alcohol or nail polish remover and vinegar
What to do
- Cut paper towel in strips
- Draw a heavy line with a marker or a couple of thin lines
- Fill cups with a bit of the chemical you are using
- Hang the paper strip over the edge of the glass so that the paper towel touches the water, but the line is above the water.
The most exciting solution proved to be the nail polish remover. It produced the most colorful strips. We were pleasantly surprised to see so much blue in black marker, and so much yellow in a green one.
And that’s five ways to try Chromatography Experiment with Kids at home.