(Exploring the Science of Automotive Air Bags)

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Air Bags (Lesson Plan)

(Exploring the Science of Automotive Air Bags)

Suggested Grade Level8-9

Standard Statements (Pennsylvania)

3.1.10ADiscriminate among the concepts of systems, subsystems, feedback, and control in solving technological problems. 3.1.10EDescribe patterns of change in nature, physical and man made systems. 3.2.10BApply the elements of scientific inquiry to solve problems. 3.2.10CIdentify and apply the technological design process to solve problems. 3.4.10AExplain concepts about the structure and properties of matter. 3.4.10BAnalyze energy sources and transfers of heat.

3.8.10AAnalyze the relationship between societal demands and scientific and technological
enterprises.

Content Objectives

Students will know that
1. Acetic acid reacts with sodium bicarbonate to produce a gas. 2. Acetic acid and sodium bicarbonate are the chemical names for vinegar and baking soda, respectively. 3. The two main purposes of an air bag are to slow a person’s forward movement into the steering wheel (or dashboard) and to provide a cushion between the person and the steering wheel (or dashboard). 4. The three parts of an air bag are the bag itself, the sensors, and the inflation system (or gas generator). 5. The main chemical responsible for the inflation of an air bag is sodium azide, which rapidly decomposes into nitrogen gas and sodium metal when it is ignited. 6. Other reactions occurring within an air bag ensure that highly reactive, dangerous byproducts are changed into stable and safe compounds. 7. The inflation of an air bag and the other chemical reactions occur in a very short amount of time (1/25th of a second). 8. The reaction between acetic acid and sodium bicarbonate is similar to the decomposition of sodium azide because both reactions produce a gas.

Process Objectives

Students will be able to
1. Provide evidence that a chemical reaction occurs between acetic acid and sodium bicarbonate. 2. Point out how the reaction between acetic acid and sodium bicarbonate is similar to the decomposition of sodium azide. 3. Create a mock air bag by determining a quantity of sodium bicarbonate that will react with 25 mL of acetic acid and inflate a zip-seal plastic bag. 4. Test their mock air bag during an egg-drop crash test and determine the maximum height that their protected egg can be dropped without the egg cracking.

Assessment Strategies

1. Evaluation of completed student handout.
2. Group presentations of completed mock air bag designs. 3. Evaluation of student essays from Part 8.

Materials

Per class
• A deflated balloon (to be blown up by you or a student) • Computer equipped with PowerPoint software
• Projector and projector screen
• PowerPoint presentation that accompanies this activity • Plastic sheet or other appropriate material to create an egg-drop crash zone Per group of students
• zip-seal baggies (~3)
• sodium bicarbonate (baking soda), ~5g
• acetic acid (vinegar), ~100 mL
• graduated cylinder
• balance
• raw eggs (can be substituted with boiled eggs for less mess) • facial tissue
• paper cup
• tape
• meter stick
Per student
• Copy of the history of air bag comic strip (pdf file)

Procedures

Part 1(1, 45-min class period)

1. Assess what the students already know about automotive air bags by having them answer the questions that appear in their Student Handout (What does an automotive air bag do?; How does an automotive air bag work; Where are air bags found?) 2. Have the students share what they wrote down.

3. Show the first seven slides of the PowerPoint presentation on air bags to help the students understand what an air bag looks like and where it is located. 4. Have the students sketch their own picture of an air bag in the box provided in their handout. 5. Have your...
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