Ever wondered why candies are different colors? Ever wondered why candies are different colors? Many candies contain colored dyes. Bags of M&Ms or Skittles contain candies of various colors. The labels tell us the names of the dyes used in the candies. But which dyes are used in which candies? We can answer this by dissolving the dyes out of the candies and separating them using a method called chromatography.
Candy Chromatography is the method of analysis of separating and comparing dyes used in candies and food coloring. It is also a proven method to analyze candy and its complex structure, without having to taste it. These complex mixtures can be separated back into pure substances. To find out the ingredients of a favorite candy, chromatography would help to define every ingredient found in the candy sample. The word chromatography is derived from the two Greek words, “Chroma” meaning color and “graphic” meaning to write. Paper chromatography is the best method of separation used in candy chromatography.
Paper chromatography is a technique that involves placing a small dot or line of sample solution onto a strip of chromatography paper.. The paper is placed in a jar containing a shallow layer of solvent and sealed. As the solvent rises through the paper, it meets the sample mixture, which starts to travel up the paper with the solvent. This paper is made of cellulose, a polar substance, and the compounds within the mixture travel farther if they are non-polar. More polar substances bond with the cellulose paper more quickly, and therefore do not travel as far.
The same color candies will have the same colored dyes which are used in making the candy. For example, the green skittle will have a green colored dye used in order to make the skittle.
1. M&M or Skittle Candies (1 of each color)
2. Coffee filter paper
3. A tall glass
5. Table salt
6. A pencil
8. A ruler
9. 6 toothpicks
10. Aluminum foil
11. An empty 2 liter bottle with the cap
1. Amount of water
2. Amount of table salt
Independent: Type of dye used
Dependent: Color of the candy
Compare the dyes between the skittles and M&M
1. Cut the coffee filter paper into a 3 inch by 3 inch square. Make six dots with the pencil equally spaced along the line. Below the line, use the pencil to label each dot for the different colors of candy that you have. 2. Next we’ll make solutions of the colors in each candy. Take an 8 inch by 4 inch piece of aluminum foil and lay it flat on a table. Place six drops of water spaced evenly along the foil. Place one color of candy on each drop. Wait about a minute for the color to come off the candy and dissolve in the water. Remove and dispose of the candies. 3. Next we’ll “spot” the colors onto the filter paper. Dampen the tip of one of the toothpicks in one of the colored solutions and lightly touch it to the corresponding labeled dot on your coffee filter paper. Then using a different toothpick for each color, similarly place a different color solution on each of the other five dots. Repeat this process three times, waiting for the spots to dry each time.
4. When the paper is dry, fold it in half so that it stands up on its own, with the fold standing vertically and the dots on the bottom. 5. Next we will make what is called a developing solution. Add ⅛ teaspoon of salt and three cups of water to your 2-liter bottle. Then screw the cap on tightly and shake the contents until all of the salt is dissolved in the water. You have just made a 1% salt solution. 6. Now pour the salt solution into the tall glass to a depth of about ¼ inch. The level of the solution should be low enough so that when you put the filter paper in, the dots will initially be above the water level. Hold the filter paper with the dots at the bottom and set it in the glass with the salt solution. 7. When the salt solution is about ½ inch (1 cm) from the top edge of the paper, remove the paper from the solution. Lay the paper on a clean, flat surface to dry. 8. Repeat this process 3 times and record your observations.
With the same colored dyes, the same candies were produced, but with a mixture of dyes, candies were also produced.
As the coffee filter paper was set in the glass with the salt solution, the salt climbed up the paper. As the salt solution climbs up the filter paper, the color spots climb up the paper too, and some colors start to separate into different bands. The colors of some candies are made from more than one dye, and the colors that are mixtures separate as the bands move up the paper. This process is called chromatography. The salt solution is called the mobile phase, and the paper the stationary phase. The word “affinity” to refer to the tendency of the dyes to prefer one phase over the other. The dyes that travel the furthest have more affinity for the salt solution (the mobile phase); the dyes that travel the least have more affinity for the paper (the stationary phase). The mixture is dissolved in a fluid called the mobile phase, which carries it through a structure holding another material called the stationary phase.
The purpose of this experiment was to use paper chromatography to see which dyes are used in the coatings of colored candies. The major findings were that the dyes were the same colors as the candies, thereby supporting the hypothesis. But, however, some of the candies were made up of a mixture of dyes, causing the colors that are mixtures to separate as the colors moved up the paper, and thereby only partially supports the hypothesis. These, however, are not the only reasons as to why the mixtures separated out as they did. Firstly, solubility: If the components of the mixture are soluble in the solvent being used, the mixture will be carried up the paper strip as the solvent travels.
If the material is soluble, the mixture will dissolve as the solvent front moves through it. If the material is a mixture of substances, some of these substances will likely be more or less soluble than others. The more soluble substances will move faster and to a greater distance than those that are less soluble. Secondly, molecular weight: Those substances of lighter molecular weight will move higher up the paper than those substances having a higher molecular weight. Thirdly, as I mentioned before, the chromatography paper is made of cellulose, a polar substance, and the compounds within the mixture travel farther if they are non-polar. More polar substances bond with the cellulose paper more quickly, and therefore do not travel as far.
If this experiment were to be repeated again, different types of candies will be used such as Sour Patch Kids, Gummy Worms, and Starbursts. Also, I would like to see the effect of chromatography on Kool-Aid, and other powdery drinks. Then, using the results from these I could compare it to the results received from this experiment. The results probably would have been more accurate this way.
“Candy Chromotography.” Candy Chromotography. N.p., n.d. Web. 10 Feb. 2013. <http://scifun.chem.wisc.edu/homeexpts/candy.htm>. “Candy Chromatography: What Makes Those Colors?” Candy Chromatography: What Makes Those Colors? N.p., n.d. Web. 10 Feb. 2013. <http://www.sciencebuddies.org/science-fair-projects/project_ideas/FoodSci_p006.shtml>. Helmenstine, A.M.( 2007). Candy & Coffee Filter Chromatography. Retrieved February10, 2013 from http://chemistry.about.com/od/chemistryexperiments/ht/candychroma.htm. Shakashiri, Bassam. Candy Chromatography (EXPERIMENT). New York: Penguin, 2002.