Instruction
Resources in Reach
Here are the resources you'll need for each activity, in order of instruction.
Assessment
Engage
1. Begin by introducing the terms exothermic reaction and endothermic reaction. Strike a portable chemical reaction stick (strike-anywhere match) and note that heat caused by the friction of the match against a surface causes the match to ignite. Also note that heat and light are released via the flame. Explain that the release of heat in a chemical reaction (or physical change) that exceeds the amount of heat used to start the reaction is an exothermic reaction.
2. Explain that, in endothermic reactions, energy must be absorbed in order for a chemical reaction to occur. Display an ice cube in a tray that has been sitting by the window or under a lamp. Note that the ice must absorb heat to convert to water. Have students write the definitions to exothermic and endothermic reactions in their journals. Inform them that they will be quizzed on all the terms learned in the lesson.
3. Tell students that they will be focusing on exothermic reactions and exploring the factors that influence a chemical reaction. They will explore these concepts by studying the chemical reactions that take place in fireworks.
Build Knowledge
1. Explain to students that, in order for fire to occur, there must be fuel, oxygen, and heat. When a fuel like natural gas (methane or CH4) has been ignited with heat (as in a lit match), the methane burns, creating a chemical change in the methane and oxygen. Chemical bonds in the methane and in oxygen from the air break and form carbon dioxide and water. Share the following equation with students:
CH4 + 2O2—>CO2 + 2H2O
2. Pass out candles to students in groups of two or three. Have students light their candles with a match or lighter. Tell students that wax, like methane, contains carbon and hydrogen. When it burns, carbon atoms join with oxygen from the air and become carbon dioxide (CO2). The process of a molecule, atom, or ion losing an electron is called oxidation. The uptake of an electron, atom, or ion is called reduction. A flame is the result of an oxidation-reduction reaction (also called a redox reaction) because both oxidation and reduction occurs. Have students write these definitions in their journals. Ask students whether they think the burning of a candle is an exothermic or endothermic reaction. (In this reaction, more heat is released than is required to break the bonds, so the action is exothermic.)
3. Tell students to divide a page in their journals into three columns. In the first column, have them write "Procedure." The second column should be labeled "Prediction" and the third column "Results."
4. Tell students they will be holding the glass jar above the candle without placing the jar on top of the candle. The candle should remain lit. Have students write down this procedure in the first column of their journals then make predictions about what they think will happen in the second column. Invite students to go through the steps of the procedure, and then write down the results in the third column.
5. Explain to students that the black soot on the glass consists mainly of carbon. Explain that carbon particles that cool quickly are not able to join the oxygen atoms and are deposited as black carbon.
6. Now tell students they will be placing the jar on top of the candle so that it encloses the candle completely. Have students write this procedure in the first column of their journals, then make predictions about what will happen. After students follow the procedure, have them write down the results. Obviously, the candle could not remain lit without oxygen. But ask students what they think would happen if we were able to provide oxygen to the candle to keep the candle lit under the jar.
7. Tell them that, after some time, the glass jar could break. Inform students that explosions occur because a chemical reaction called combustion has taken place. In combustion, oxygen reacts with a substance such as fuel. The process of rusting, in which iron oxide in a metal reacts with oxygen from the air, is an example of slow combustion. Rapid combustion results when there is a rapid release of heat. If the release of heat and gas is extremely rapid, and the gas cannot dissipate quickly enough, then extremely rapid combustion and explosions occur. This is the basic process involved in the creation of fireworks. Students should write the definitions of slow combustion, rapid combustion, and extremely rapid combustion in their journals.
8. Reinforce the concepts of combustion and oxidation reactions by inviting students to explore the On Fire section of PBS's NOVA Online site, Fireworks!, either individually in a computer lab or as a class via a digital projector.
Apply
1. Inform the class that combustion in fireworks displays occurs in fireworks shells, which contain gunpowder (a mix of sulfur, charcoal, and saltpeter) and other chemical powders that will create the colorful sparks when the shell ignites. Tell students that saltpeter is the oxidizer, meaning it provides the oxygen necessary for combustion to occur. When a pyrotechnician sends a spark to the shell, the saltpeter releases oxygen, and heat and gas are produced. Gas caused by the combustion cannot dissipate quickly within the confined shell, so pressure builds up in the shell. When the gas can no longer be contained, the shell bursts and a colorful fireworks display explodes in the sky.
2. Have students read "The Making of a Shell" on ARTSEDGE's Look-Listen-Learn resource Art of the Explosion: Pyrotechnics & Fireworks. As they read, they should take notes on the information in their journals.
3. Once students understand the basics of the construction of fireworks shells, inform them that they will be exploring what factors influence the outcome of the chemical reactions. Ask them to venture a guess at the following question: What creates a bigger explosion, and what affects the shape, color, and height of the fireworks display?
4. Have students click on "Create Your Own Fireworks" on Art of the Explosion under "how does it work?" and then click on "size of explosion." As a class, discuss the concepts learned. You may wish to reinforce the concept that surface area affects the outcome of a chemical reaction by conducting the Antacid Tablet Race activity on NASA's Rockets Teacher's Guide.
5. Have students follow along with the other animations under "how does it work?" As they read about color, shape, and timing, students should take notes in their journals. You may wish to study each concept in a more in-depth way. To further explore the chemistry involved in color, and more deeply study the art of pyrotechnics, see some of the activities in the ARTSEDGE lesson, Science Meets Artistry: The Work of Cai Guo-Qiang. You might also discuss shape and timing through the exploration of Newton's Laws of Motion. For a great online resource, see Newton's Laws of Motion on the Web site of NASA's Glenn Research Center.
6. Discuss with students that pyrotechnics is not just a science—it is also an art. Pyrotechnicians consider how the overall event will look before making final decisions about color, size, etc. of individual fireworks.
7. Review the following organizational principles in visual art:
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Repetition: refers to a way of combining design and composition elements in artworks so that the same elements are used over and over again.
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Balance: the pleasing distribution of objects, colors, textures, and space on a design. A design may have symmetrical, asymmetrical, or radial balance.
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Emphasis: refers to the part of a composition that catches a viewer's attention. If there is an area of emphasis in a work, the viewer's eye will focus first on this area, then take in the rest of the composition.
If students are being introduced to these concepts for the first time, you may wish to explore the site, The Artist's Toolkit: Visual Elements and Principles, with students. (See the links under "Visual Principles," specifically "Emphasis," "Movement/Rhythm" for information on repetition, and "Balance.")
8. Introduce the artist Cai Guo-Qiang to students. Inform students that Guo-Qiang creates "explosion events," ephemeral works that incorporate pyrotechnic technologies. Show students the video of Tornado: Explosion Project for the Kennedy Center (see the "Ignite" section of Art of the Explosion).
9 .Tell students that although they cannot build and ignite their own explosion events, they can conceptualize and choreograph an event using the interactive activity on
Art of the Explosion .
Have students practice using the interactive by replicating the rainbow shape that Guo-Qang has used in several works—Transient Rainbow (2002), Black Rainbow: Explosion Project for Edinburgh (2005) and Black Rainbow: Explosion Project for Valencia (2005). Direct students to the image of Black Rainbow: Explosion Project for Valencia for a model (located in the "Dancing Boats" section of "Vision" in the "Conceptualize" section of Art of the Explosion).
10. Once students have a feel for using the interactive, give them time to conceptualize their own explosion event. Students should pay attention to the principles of organization when designing their explosion events. Their events must demonstrate their knowledge of repetition, balance, and emphasis.
As students choreograph their own explosion events, tell them to keep careful notes in their journals about which effects are successfully working so that, later, they can recreate the event for the whole class later on. (Note: information on the interactive activity will not be saved once the web-browsing window is closed.)
Reflect
1. Have each student present the explosion events they created on the Art of the Explosion interactive activity.
2. After all the students have presented their events, discuss the process they went through to create them and what they learned about art and science while doing this.
Assessment
1. Quiz students on the vocabulary learned in this lesson.
2. Assess the students' final projects based on the following criteria:
- Demonstration of knowledge of organizational principles.
- Creativity and evidence of thoughtful planning.
- Successful use of technology to implement ideas.
3. Use the Assessment Rubric that can be found within the Resource Carousel to evaluate students' work.
Key Vocabulary
- Gas
- Heat
- Endothermic
- Exothermic
- Methane
- Carbon dioxide
- Combustion
- Oxidation
- Pyrotechnics
- Repetition
- Balance
- Emphasis
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