What do the Grand Canyon, a peacock's tail, red apples, and a bouquet of flowers have in common? Colors!

To begin the study of colors and chromatography, your students will need to start with the primary colors - red, blue, and yellow. The primary colors can be combined to give us an infinitesimal array of colors. A rainbow shows us the separation of light in its many colors. White light is a combination of all the colors. A tint is produced when white is added to a color. Black added to any color will produce a shade, and gray added to any color makes a tone. Pigments are colored compounds in plants or paints that produce a color. Dyes are colored substances that have a staining effect, but can be dissolved in liquids or separated from pigments.

These concepts will be easier for your students to understand when they mix simple food coloring dyes in this activity and create color "magic" right before their eyes. They can then separate these dyes through paper chromatography.

Chromatography is the process of separating substances in mixture (such as the different food coloring in this experiment). In paper chromatography, this is done by placing filter paper that has been stained with a drop of the mixture into a solvent (water) so the various substances can be separated and identified. Chromatography is colorful, and your students will enjoy watching the separation of these colored dyes as they migrate up the filter paper. At the same time, your students will use the step-by-step procedure of the scientific method.

The scientific method is the framework used by scientists to carry out an experiment in a methodical way. It helps your students state a problem and hypothesis, predict the outcome of an experiment, perform the experiment, reach conclusions, and make suggestions for further experiments to verify their conclusions. You'll find that when your students use the scientific method, their papers will show you not only their thoughts, methods, and procedures, but also will give you a better way to evaluate their conclusions.

1. Pour water into a plastic cup to a depth of 1 cm (about 20 mls). Then cut a rectangle of filter paper about 12 cm by 10 cm. With a pencil, draw a straight line across the width of the rectangle 1 cm from the bottom of the paper. Using the tip of a toothpick, place a small dot of each Kool-Aid solution on the line, leaving a space of at least 1.5 cm between each dot.
1. Form a cylinder with the filter paper, and pass a plastic straw through two slits cut into the sides of the cylinder (see Figure 1). You will need to adjust the size of our cylinder to the size of your plastic cup. (Alternatively, you can cut the filter paper rectangle into individual strips.) Suspend the filter paper so it does not touch the sides of the cup, and so that the bottom of the paper touches the top of the water level. The dots of dye must remain above the water level, otherwise your water will be contaminated and you will have to start over.
1. Wait for your chromatogram to develop. When the water has reached the top of the paper, your chromatogram is finished developing. Remove the paper and allow it to dry. Clean up while you're waiting, and write your observations and results on Handout2. Then check your results against the "Kool-Aid Dye Table" on Handout 3. Not how your results compared with the table.
1. Construct a chart, table, or graph showing a comparison between the dyes that were soluble and those that were insoluble. Use graph paper for charts or graphs. You may also want to include in your results any shades, tints, or other colors that surfaced in your experiment. Include your chart, table, or graph in the "Results" section of Handout 2. Then write your conclusions.