If your family is like ours, summer means more sweet treats and more candies in the cupboard! Here’s an opportunity to put those candies to another use. Using a scientific technique called CHROMATOGRAPHY, this experiment uncovers the different mixtures of dyes that make up colorful candy coatings.
Chromatography is the chemistry of separating a mixture into its individual components. Mixtures are made up of two or more substances that keep their original properties when combined. For this reason, they can be separated or un-mixed!
There are many different kinds of chromatography. Scientists use chromatography in the lab to separate and analyze all sorts of different mixtures, including liquids, gases, proteins, and carbohydrates. Chromatography is also used as a tool in forensic science to identify substances from crime scenes.
In this experiment, you will use coffee filters and water to separate the dyes in candy coatings.
WHAT YOU’LL NEED
LET’S GET STARTED
(See photos below for experimental set-up.)
What did you see? Did different colors give different patterns? How did the patterns from the primary colored candies (red, yellow, blue) compare to the other colors? Why do you think this is?
WHAT’S GOING ON?
In this experiment you used paper chromatography to separate the mixture of dyes that make up candy coatings. The filter paper is called the stationary phase. The water is the mobile phase. Water moves up the filter paper by a process called capillary action. As the candy coating dissolves in the water, the pigment molecules from the dye are pulled along with the water and move up the paper. The pattern of colors on the filter paper is called a chromatogram.
You probably saw that some of the candy dyes were a mixture of several different pigments or colors. In our experiments at Yellow Scope, we saw that the brown and green candies were made up of several different pigments, but the dyes of the primary colored candies, like red and yellow, showed only one color.
You also may have noticed that some pigments moved farther up the filter paper than others. How far they move depends on the size of the molecule and how attracted they are to the paper. Some pigment molecules stick to the paper, so they don’t move as fast or far up the paper. Smaller molecules tend to move farther up the paper than larger molecules.
MIX IT UP!
Try more chromatography experiments with other dyes like colored markers. We find that brown and black washable markers show the most interesting pattern of colors. Compare different brands of markers. You also can use chromatography to separate the dyes in food coloring, powdered gelatin, or powdered drink mixes
For another variation, try adding salt to the water to see if salt affects the pattern of colors. Some pigments may interact with the ions in the salt water and to produce a different separation of colors.
The Yellow Scope Team
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