Subject: High School Chemistry
Grade Level: 11th grade
How it Works: The Chemistry of Color is a 5-to-6 day unit designed to incorporate the preparation of pigments and binders for paint into the standard high school chemistry curriculum to more closely tie in the material in the chemistry class with real-life applications. In the unit, the students learn how to prepare pigments from precipitates derived from double replacement reactions, and then to combine it with solutions and binders to derive paint which can be applied to painting surfaces.
Final Project/Product: The curriculum was developed from the teaching manual "Art in Chemistry; Chemistry in Art" Written by Barbara Greenberg and Diane Patterson. The lesson plans are derived from Chapters 2 and 3 from the book.
Overall Value: In my experience the chapters in textbooks regarding Solutions and Solubility have covered the subject adequately, but without any real connections between the need for solutions and what the students see in their real life. Often the subject lends itself to talking about anti-freeze and battery acid and little connection is made with objects that most teenagers would pay attention to. However, by connecting solution information to paints and paper,which the students have used throughout their school years has the overall benefit of being familiar yet suddenly mysterious to the students. Hopefully, that when the students connect the chemistry to creating paint they will begin to look on the importance of learning solutions and try to see the connections between chemistry and artwork.
Tips for the Teacher: 1) If you attempt to create paint in the classroom, you must have an adequate flow of air either through windows or exhausts. The smells, especially from linseed oil will overcome students especially since they will be working at close range with the material. 2) If you use egg tempera, please be sure to keep the egg yolk clear from albumen. This will create a clearer and more distinct color intensity from the pigment without runny lines. The yolk alone will also give the paint a thick consistency which will transfer to the paper more completely. 3) Note that the binders chosen will last for many days with the exception of egg yolk. Once the students use this medium as a binder, they should spray their work with laquer or fixative to permit the work to be displayed for an extended period.
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| New York State Standard 4 -- The Physical Setting: Students will understand and apply scientific concepts, principles, and theories pertaining to the physical setting and living environment and recognize the historical development of ideas in science. |
| Grade: 11th grade Subject: Chemistry |
| NYS Standard 4 -- Key Idea 3: Matter is made up of particles whose properties determine the observable characteristics of matter. |
| Grade: 11th grade Subject: Chemistry |
| NYS Standard 4 Key Idea 3.3: Apply the principle of conservation of mass to chemical reactions. |
| Grade: 11th Grade Subject: Chemistry |
| NYS Standard 4 -- Key Idea 5: Energy and matter interact through forces that result in changes in motion. |
| Grade: 11th Grade Subject: Chemistry |
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| Day 1: The Colorful History of Paint |
| Objectives |
| Students will understand that modern paint is a combination of natural chemicals and acrylics. |
| Students will determine that a solution is a homogeneous mixture of two or more substances. |
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| Materials |
| Graph paper |
| Pen or pencil |
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| Procedure 1 |
| Display prints of paintings of different historical periods. One should be ancient such as Egyptian or Greek. Other historical periods include Roman, Middle Ages, Renaissance, Romantic, Impressionist, and Modern eras. |
| A Timeline of Art History from the Metropolitan Museum of Art is an excellent resoucre for viewing period art and historical information. http://metmuseum.org/toah/splash.htm |
| Procedure 2 |
| After displaying the pictures, discuss the kinds of paints produced by the artists to realize their ideas. Explain that in many cases the decisions of the artists as to color and texture were based on the limitations of the materials available. |
| The British Museum link offers an easy search tool to locate art from many historic periods. http://thebritishmuseum.ac.uk/world/world.html |
| Procedure 3 |
| Plan and produce a timeline of painting examples illustrating the improvement of pigments and binders and the artists that used them. |
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| Procedure 4 |
| Discuss with students the advantages paint has in covering an area with a homogeneous substance. |
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| Procedure 5 |
| Review the parts of paint (pigments and binder) and develop ideas about why paint covers an area. |
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| Day 2: Solutions and Color Intensity |
| Objectives |
| Students will compare and contrast the physical properties of unsaturated, saturated, and supersaturated solutions. |
| Students will evaluate paint color intensity in the context of each type of solution. |
| Students will discover the effects of temperature change on solute solubility and color intensity. |
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| Materials |
| For each student group: |
| 14.5 grams sodium acetate, Three large test tubes, Test tube holder, Bunsen burner or alcohol lamp, Matches, |
| Celsius thermometer, Distilled Water, Tubes of red and blue watercolor paint pigment, Stirring rod, |
| Test tube rack, 10-mL graduated cylinder, Centigram balance, Paintbrushes, Watercolor paper |
| Procedure 1 |
| Part A: Students prepare unsaturated, saturated and supersaturated solutions of sodium acetate: Saturated solution: In a large test tube, dissolve 4.65 grams of sodium acetate in 10.0 mL distilled water at 20 degrees Celsius. |
| a. Unsaturated solution: In a large test tube, dissolve 3.0 grams of sodium acetate in 10.0 mL distilled water at 20 degrees Celsius |
| b. Supersaturated solution: In a large test tube, add 7.0 grams sodium acetate to 10.0 mL distilled water and gradually heat the test tube contents over a Bunsen burner or alcohol lamp until all the sodium acetate is dissolved. Carefully place the test tube into a test tube rack and let it cool without being disturbed. All the sodium acetate will remain in solution. |
| c. Observe the appearance of all three solutions, recording observations. Add a small crystal of sodium acetate to each test tube, observe and record observations. |
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| Procedure 2 |
| Part B: Students will experiment with temperature change and color intensity. Fill each of two test tubes with 1.0 mL distilled water. |
| a. Heat the water in one test tube to about 50 degree Celsius. |
| b. Add watercolor pigment to each test tube until no more pigment will dissolve. |
| c. Observe the appearance of each solution and record observations. |
| Assessment |
| Please see assessment for Day 3. |
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| Day 3: Solutions and Color Intensity II |
| Objectives |
| Students will discover the effects of temperature change on solute solubility and color intensity. |
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| Materials |
| Three large test tubes, Test tube holder, Bunsen burner or alcohol lamp, Matches, Celsius thermometer, Distilled Water, |
| Stirring rod, Test tube rack, 10-mL graduated cylinder, Centigram balance, Paintbrushes, Watercolor paper |
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| Procedure 1 |
| Part C: Painting using solutions: Paint two small pictures having chemistry themes in saturated, unsaturated, and supersaturated solutions. |
| a. For one, use the room-temperature paint; for the other, use the paint at 50 degrees Celsius. |
| b. Make a list of differences between the two paintings. Compare the two paintings, noting differences in color intensity and the effect of the color intensity differences on the general appearance and the message contained in the paintings. |
| Extension |
| Students may want to photograph the entire process and prepare a classroom "art journal" that would feature contributions from the students explaining exactly how their art project grew from start to finish. The articles would be similar to other articles in a mature art composition journal, but would be focused to the student's level of expertise in the class. |
| Assessment |
| 1. What was the appearance of each sodium acetate solution before a crystal of the compound was added? 2. How did the solutions change when the crystals were added? In some cases, did the solutions become heterogeneous (non-uniform) mixtures? 3. In paints, the pigment is the solute and the binder is the solvent. Should a paint solution be unsaturated, saturated, or supersaturated? Why? 4. Imagine paint solutions that are unsaturated, saturated, and supersaturated. How would color intensity appear in each solution? 5. How does an increase in temperature affect the solubility of a solute in a solvent? 6. Was the color more intense in the room-temperature watercolor solution or in the 50 degrees Celsius watercolor solution? |
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| Day 4: Preparation of Colored Pigments |
| Objectives |
| Students will prepare paint pigments from a variety of materials. |
| Students will write balanced chemical equations for the preparation of selected paint pigments. |
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| Materials |
| Mortar, Pestle, 100 mL Beaker, Evaporating dish, Funnel, Filter paper, Tongs, Three small test tubes, Bunsen burner or candle, Pea-size amount of azurite, 3.0 g Lead nitrate, 1.5 g Sodium chromate, 25.0 mL Graduated cylinder, Distilled water, Centigram balance, Four small test tubes, Small spatula, Wash bottle, Two 100 mL beakers. |
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| Procedure 1 |
| Have students prepare color pigments from two minerals: |
| a. Place a pea-size portion of azurite in a mortar. |
| b. Using a pestle, grind the mineral to a fine powder. |
| c. Save the powder in a small test tube. |
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| Procedure 2 |
| Have students prepare a color pigment from combustion of a hydrocarbon. |
| a. Light the Bunsen burner or candle. The flame should be yellow. If using a Bunsen burner, adjust the air inlets. If using a candle, removal of oxygen will create yellow flame. (Most candles will burn with a yellow flame.) |
| b. Using tongs, hold the bottom of an evaporating dish about 4 inches above the flame until a black deposit appears on the bottom of the dish. |
| c. Using a spatula, scrape the black deposit into a small test tube. |
| d. Save the deposit. (Use the test tube as a container.) |
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| Procedure 3 |
| Have students prepare a color pigment from aqueous ion precipitation: |
| a. A) Dissolve 3.0 g lead nitrate and 1.5 g sodium chromate separately in 25.0 mL distilled water each. (Use a 50 mL graduated cylinder for measuring the water.) B) Combine both solutions in a 100 mL beaker. |
| b. Fold the filter paper to fit the funnel, set up the funnel for filtering, and pour the combination of the solutions into the filter paper. Use a 100 mL beaker to collect the filtrate. |
| c. A) Using a water bottle, squirt distilled water into the residue allowing this wash water to seep through the filter paper and become part of the filtrate. B) Discard the filtrate into a container for safe disposal. |
| d. A) Unfold the filter paper and allow the residue to dry. B) Save the residue |
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| Extension |
| Students may prepare the paints and other art materials for the lab and bring them to another class of younger students to create art work from these materials. The students each work with a group of younger students and explain to them how the materials were created (This requires that the chemistry students be able to grasp the theories behind solutions) and lead the students in putting the materials to the use in art. |
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| Day 5: Preparation of Binders |
| Objectives |
| Students will prepare a variety of binders and describe their physical properties. |
| Students will explain the requirements for a binder in a paint. |
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| Materials |
| Linseed oil, Turpentine, Beeswax, 3.0 g Ammonium carbonate, Egg yolk, Soluble starch, Distilled water, 10 mL Graduated cylinder, Four 250 mL beakers, Small test tube, Bunsen burner, Stirring rod, Four watch glasses, Paint brush, Centigram balance. |
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| Procedure 1 |
| Have students prepare a binder for oil paint: |
| a. Using a 10 mL graduated cylinder for measuring, combine 2 mL linseed oil and 4 mL turpentine in a 250 mL beaker and stir. |
| b. Save the binder. (Use the beaker as a container.) Cover the beaker with a watch glass. |
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| Procedure 2 |
| Have students prepare a binder for water-soluble paint, using wax for permanence. |
| a. Place a 1-inch cube of beeswax and 30 mL distilled water into a 250 mL beaker. |
| b. Heat gently over the colorless flame of a Bunsen burner until beeswax melts. |
| c. Add 3.0 g ammonium carbonate a little at a time, while gentle heating is continued. Decrease the heat if the solution threatens to foam over the top of the beaker. |
| d. Save the binder. (Use the beaker as a container.) Cover the beaker with a watch glass. |
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| Procedure 3 |
| Have students prepare a binder for egg tempera paint> |
| a. A) Separate an egg yolk from the albumen. Discard the albumen. B) Carefully place the egg yolk in hand and pass it from one hand to the other, without puncturing it, until it is fairly dry. |
| b. A) Place the egg yolk in a 250 mL beaker and puncture it. B) Transfer the egg yolk to a 10 mL graduated cylinder and measure the volume. |
| c. Add to the egg yolk an equal volume of distilled water and stir the mixture until it is homogenous (has a uniform consistency). The mixture should have a thick consistency. |
| d. Save the binder (use the beaker as a container). It will keep for a day or two in the refrigerator but it has a very brief shelf life. |
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| Procedure 4 |
| Have students prepare a binder that covers well for temporary purposes. Then make the binder more permanent 1. 2. 3. 4. |
| a. In a 250 mL beaker, add 2.0 g starch to 4.0 mL cold distilled water and stir to make a paste. |
| b. Boil 4.0 mL distilled water in a test tube over the flame of a Bunsen burner. Add this to the starch paste, stirring well. This solution is a temporary binder. |
| c. To the starch solution, add 2.0 mL linseed oil, a little at a time, while stirring. This solution is a permanent binder. |
| d. Save the binder. (Use the beaker as a container.) |
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| Extension |
| The most fun way to assess this project and bring it to a close would be an art show or exhibit using the students' work as the focus of different competitions. However, since this is a chemistry lesson, the judgment on the works has to be on the overall presentation of the work especially, the students' explanations of what was happening in the different chemical reactions that produced the materials for the work. Often, I require students to present their material for display as if it was a museum piece and require that they create an "exhibit card" for the work that details how and why they decided to use a specific color blend or binder for their work and how it chemically creates the presentation that they anticipated. |
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James Kopchains
j.kopchains@lycos.com
Flushing High School
35-01 Union Street
Flushing, NY 11354 |
