Chromatography: Solar Photography (page 2)
Design Your Own Experiment
CAUTION: Keep the alcohol away from your nose and mouth.
Place the rounded edge of the paper cone into the alcohol. To prevent the alcohol from evaporating too quickly, cover the paper and saucer with a 2-liter plastic soda bottle that has a cap and its bottom cut away (see Figure 17.2). Allow the paper to sit undisturbed for 30 minutes. Study any colored streaks on the paper and identify the pigments:
- Is chlorophyll the only color pigment in a leaf? Make a dark green mark about 1 inch (2.5 cm) from the rounded edge of a paper coffee filter by placing a leaf, top side down, on the paper and rubbing the edge of a coin back and forth over the leaf. Allow the green mark on the paper to dry before repeating the process. You want to collect enough pigment from the leaf to make a dark green line on the paper. Fold the paper filter in half twice and secure with a paper clip to form a cone. Pour a small amount of rubbing alcohol into a saucer.
- chlorophyll (a)—blue-green
- chlorophyll (b)—yellow-green
- What makes a red apple red? The red color of an apple is from the color pigment anthocyanin. Other plant pigments are located in plastids, but anthocyanins are found in cell sap. Anthocyanin is red in the acid solution of the cell sap, giving the skin of the apple a red color. Anthocyanin can be separated by boiling the peeling from a red apple in 1 cup (250 ml) of distilled water. The resulting pale color of the cooked peeling and water is due to the neutralization of the acidic cell sap by the basic content of the ruptured cells. Add vinegar (an acid) to the liquid in which the apple skin is boiled to test for the presence of anthocyanin.
- Would the color of anthocyanin be affected differently if the cell sap was alkaline? Test the effects of an alkaline on the color of anthocyanin by adding drops of household ammonia or limewater to the liquid that the peel of a red apple has been boiled in. See Appendix 2 for instructions on making limewater.
CAUTION: Ammonia is a poison. It and its fumes can damage skin and mucous membranes of nose, mouth, and eyes.
Get the Facts
- Chlorophyll produces the green color in plants, but other colored pigments also exist in green leaves. Find out more about plant color pigments. What causes the brilliant color changes in leaves during the fall? What environmental conditions produce the most colorful leaves? What is the pigment's function other than producing color?
- Minor changes in a chemical formula can make major changes in the physical and chemical properties of a substance. Chlorophyll and hemoglobin are amazingly alike. Both contain 137 atoms. A replacement of one atom could change hemoglobin to chlorophyll and vice versa. Find out more about chlorophyll and hemoglobin. How do the two molecules compare structurally? Draw and display a structural diagram for comparison. What function does each play in the energy-producing reactions with which each is involved?
Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state’s handbook of Science Safety.