| Objective | | | | the form of a spot on the origin line on the |
| The aim of this experiment is to find out which colors | | | | chromatography paper. |
| are used to coat well-known colored candies using a | | | | 4. After the spot dries, repeat the same procedure |
| technique called color chromatography. | | | | three times more in order to place sufficient dye on |
| Introduction | | | | the paper and allow it to separate out. Make five |
| A method that science fair experiments use to | | | | different strips in the same way. We make 5 different |
| differentiate between various components of a | | | | strips to get five different Rf values and then find the |
| mixture or solution is called chromatography. In case | | | | average, something that is often done in science fair |
| you have a colored mixture, paper chromatography | | | | experiments. |
| can help you see each color component differently on | | | | 5. Now repeat steps 3 and 4 for the second colored |
| the paper. | | | | candy that needs to be tested. |
| Do you remember what happened the last time when | | | | 6. Repeat step 3 and 4 for the third colored candy |
| a water drop fell on your inkjet printout? The water | | | | that needs to be tested. |
| spread along the capillaries of the paper, and in the | | | | 7. Now take some known food dyes and repeat |
| process it carried along with it the particles of ink, giving | | | | steps 3 and 4 for each dye. |
| your printout a smudged or blotted look. The same | | | | 8. Prepare 1% salt solution as a chromatography |
| process that ruined your printout can be used in | | | | solvent by dissolving 1/8th teaspoon of salt in 3 cups |
| science fair experiments for a good purpose. Again, | | | | of water. |
| this process is known as paper chromatography. | | | | 9. Pour just a little amount of this solution in a |
| In this experiment you will compare the Rf value of | | | | wide-mouthed jar. |
| food dyes used in colored candy with the Rf value of | | | | 10. Tape your spotted chromatography strip onto a |
| components of food dyes that you know. | | | | pencil. Now place the pencil on the mouth of the jar in |
| Material | | | | such a way that the strip just touches the solvent |
| M&M candies, minimum 30 paper strips, | | | | surface. |
| wide-mouth jar, ruler, pencil, salt, tape, toothpicks, water, | | | | 11. Allow the solvent to rise up due to capillary action, |
| red, blue and green food colors. | | | | taking with it particles of the dye. Once it has almost |
| Note: Use paper strips of size 3cm x 9cm or | | | | reached the top remove the strip and mark the height |
| whichever size suits you. All strips should be of the | | | | the solvent has travelled by using a pencil. |
| same size. You may use white coffee cone filters or | | | | 12. After the strip dries, the Rf value for every candy |
| special chromatography paper. | | | | color must be measured. The same must be done for |
| Procedure | | | | the known food dyes. |
| | | | 13. The average Rf of the 5 repeated strips of each |
| 1. Mark each paper strip with the color that you will | | | | candy color must be calculated. The same must be |
| apply on it. | | | | done for the known food dyes. |
| 2. Mark a 2 cm border at the bottom of each strip | | | | 14. Compare the Rf value of the candy colors with |
| placed vertically by using a pencil. This line will be used | | | | those of the food dyes. Which candy color matches |
| as the origin line where you will apply a spot of the | | | | which food dye? |
| candy color. | | | | Record your findings to show the exact colors |
| 3. Now dissolve some dye from the candy to be | | | | contained in each candy as the success of science |
| tested. Place a candy on a water drop on a flat plate. | | | | fair experiments depend upon the data recorded and |
| After about one minute, remove the candy. Dip a | | | | the results displayed. |
| toothpick in this colored drop. Apply the candy color in | | | | |