You may be part of a group for the first part of this exercise. Each group should carry out the experiment and collect the data together, but each student must record the data in his or her own booklet. Be sure to record the data exactly as you observe them. After the data has been collected, each student should answer the questions independently.

After you have finished your experiment and have recorded all of the data, you will be asked to answer some questions about the experiment and the data you recorded. Your answers must be written in this test booklet in the space provided. Make sure that you understand each question before you begin to write. At any time while you are writing your answers, you may look back to the directions for the experiment and the data you collected. Be sure that your answers are written as clearly and neatly as possible.

Before you turn the page, read the list of materials given below and check to make sure that your group has everything listed.

In developing a food product, you would want to consider the chemical content of its ingredients. For instance, since consumers with certain allergies may need to know about the dyes used in food, you should be able to identify the dyes in your product.

Paper chromatography is a process that can be used to separate the components of a mixture. The advantage of this process is that relatively small quantities of substances, including food components, can be detected in a simple and fast manner. Mixtures or solutions of metals, dyes, blood, urine, or antibiotics, for example, can easily be separated by the various chromatographic methods available to chemists today.

In this activity you will apply the analytical technique of paper chromatography to examine the dyes found in the colored shells of candy.

Read all of the instructions before proceeding. You will be working with a partner while performing the experiment and collecting the data. Both partners are responsible for recording the data. You will be working alone while responding to the questions. Your teacher will tell you where all the materials you need are located.

• Be careful to handle the filter paper only by the edge.

• Draw a horizontal line in pencil approximately 1.0 cm from the short end of each strip of filter paper. Lightly draw a dashed line approximately 2.0 cm from the opposite end.

• Add tap water to the cup to a depth of about 0.75 cm. The water level in the cup must be below the level of the first line you drew.

• Moisten a green, yellow, or brown candy. Now rub the candy's coating on the filter paper. Your goal is to transfer colored coating onto the paper. Transfer colored coating onto the paper in the area just above the first pencil line you drew.

• Repeat this procedure so that you have green, yellow, and brown candy coatings on three different strips of filter paper.

• Make sure that the chromatography paper has thoroughly dried before proceeding further and that you have labeled each strip with a G, Y, or B to help you remember what color coating is on each strip. The labeling should be done at the top of the strip above the dashed line.

• Carefully lower each strip into the water in the cup. Do not lower any of the strips beyond the 1 cm pencil line you marked previously. Hold each strip in place until the water has risen on the strips to the dashed line, or for 5 minutes (whichever comes first). Tip: It may be more convenient for you to do one strip at a time.

• Do not throw your chromatography strips away. You will need to analyze the results in Question 1.

• After you have finished, be sure to clean up your work area.

1. Describe the components of each dye used in the candy coatings based upon the chromatography you have just performed.
   
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2. Organic chemists, as well as other scientists, often use this technique to determine if a chemical reaction has occurred or to separate the components of a mixture. Explain, using an example, how and why the result from this type of analysis are useful.
   
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