Put the scientific method on hold, save the science fair tri-folds for later, it's summer time and a few easy to find materials will add some discoveries to the day. There are many scientific explorations these two experiments can lead to, but if your kids have the 'lazy summer days' feeling like mine do, the end result may be making some pretty chalk in the end and a few intellectual seeds planted for later investigations.
The first one is the common "Celery Experiment." All it takes is a celery stalk or two and some food coloring dye. Cut a fresh slice off the bottom of the celery stalk and plop it in to a glass with some food coloring. Questions will rise along the way, and best guesses will be added naturally. What color dye will show the best coloring? What if instead of water, we use another solvent….like Rubbing Alcohol?
The next one is "Chalk Chromatography Experiment." Rubbing Alcohol is the solvent used in this experiment. It can be found at your local drugstore and also goes by 70% Isopropyl alcohol and you will need the "colorless" version of this. Also needed, a pack of white chalk, some colored permanent markers and a few glass jars. Mark a thick solid circle around the circumference of the chalk about 3/4 inch above the bottom with one of the permanent markers. Mark a second one with a second color and continue with the third chalk and third color. Add these to a jar that has a level of rubbing alcohol that will be slightly below these lines. Keep them standing up on their end and wait. The rubbing alcohol will slowly rise up the chalks and will bring the different colors of the line up at different rates.
Kids still interested?
Add some Art Concepts in there as well. The blue chalk will not separate into colors because it is a primary color. The secondary colors green, orange, purple will add a much more colorful display.
More science?
This is similar to a chromatography experiment taught in college organic chemistry labs. For example the pigment in spinach will separate into an array of orange, yellow and green colors. Chromatography is also used in a number of sciences including the environment (ion chromatography), forensics and more.
Why do certain colors travel further than others? Hypothesize away.
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