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Systems and Scale | Activity 5.4

Activity 5.4: Explaining Other Examples of Combustion (50 min)

Students choose—or you choose for them—two examples of other fuels, then use the forms and procedures they used for ethanol to explain the combustion of those other fuels.

Resources Provided

Setup

Print one copy of 5.4 Explaining Combustion of Organic Materials Worksheet for each student before class. Prepare a computer and projector to display the PPT.

Directions

1. Use the instructional model to show students where they are in the course of the unit.

Assessment

Assessment takes place in Step 1 when you ask students to discuss the general characteristics of combustion of organic materials. At this point, students should articulate a general pattern of what happens when organic materials burn. Students should be able to articulate the patterns for each of the Three Questions at this point. You can review previous activities if this is difficult for students.

Assessment also takes place in Step 4. Listen to the ideas your students offer as they construct a class explanation for what happens when ethanol burns. Are they able to use precise language when describing atoms, molecules, bonds, and different forms of energy? Are they able to explain this at both macroscopic and atomic-molecular scales? Do they trace matter and energy through the chemical change? Use this conversation to determine if your students are prepared for the unit posttest, which takes place in the next activity. 

Use 5.4 Grading the Combustion of Organic Materials Worksheet to grade your students’ work on the 5.4 Explaining Combustion of Organic Materials Worksheet.

Tips

Emphasize the similarities among the explanations of all organic materials burning. There are different fuel molecules, but the same kinds of atoms, bonds, reactions, and forms of energy. The same rules and patterns apply to all examples of burning organic materials.

Modifications

  • Use molecular models for this activity if your students had difficulty developing a full account of ethanol burning.
  • Have students select which fuel they would like to complete in step 2.

Extending the Learning

  • Have students construct a model that shows the combustion of other materials with the molecular models, and use those models to write balanced chemical equations. Have students explain combustion of other organic materials that they choose. They can find structural formulas for many organic materials on the Internet.
  • Use the Net Logo model of methane combustion to further understand the chemistry and kinetics of combustion. http://ccl.northwestern.edu/netlogo/models/community/Combustion%20of%20Methane