This is a very easy experiment for kids, to teach them about the different pigments that make up the colors in pens. For this experiment, you will need the following:
- coloring pens
- blotting paper (kitchen towels can do the trick as well)
First cut out the blotting paper or kitchen towel into a size big enough to fit around the inside of the glass.
Aya then draws five one-cm circles of color on the paper.
Water is poured into the glass, until it is about 1 or 2 cm deep. Aya adds and stirs about a teaspoon of salt.
The paper is then rolled into a tube and placed inside the glass. Leave it for about 30 minutes and watch what happens!
Here is the result for the brown color: you can see that the colors split as they are drawn through the paper. (Sorry for the hole; Aya got too enthusiastic drawing that circle, haha.)
Explanation: The colors used in pens are made up of several different substances called pigments. Different pigments move through the paper at different speeds, which shows the various shades that make up the colors. This process is called chromatography. A more technical explanation is given as follows:
Chromatography is method of separating mixtures and identifying their components i.e. it’s a separation method that exploits the differences in partitioning behavior of analytes between a mobile phase and a stationary phase to separate components in a mixture. Components of a mixture may be interacting with the stationary phase based on charge (ion-ion-interactions, ion-dipole-interactions), van der Waals’ forces, relative solubility or adsorption (hydrophobic interactions, specific affinity).
We repeated this experiment with a different set of colors.
Here is the final outcome for the second trial. As you can see in the above results, dark colors such as black and brown do contain the most pigments!
Parents, how about trying this simple experiment at home with your kids?