Climate Change: Carbon Dioxide Data Analysis
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This activity is designed for use in a General Chemistry course in conjunction with the introduction of molecular structure and bonding, molecular shape, dipole moment, and infra red spectroscopy. It explores the concentration of selected greenhouse gases geographically and as a function of time. Students are asked to use a simple model to project future greenhouse gas concentrations and the uncertainty in those projections. This activity applies basic chemical principles and quantitative reasoning, while making links with biology and geology, in the context of an environmental issue of current importance.
This exercise will introduce the science student to the details of what makes a gas a "greenhouse" gas and will provide the student with data on the historical gas concentration. The chemistry principles introduced/reinforced will include molecular connectivity (Lewis structures), 3D shapes (VSEPR), and dipole moments. During the introduction to this activity, the student will be presented with an analysis of the most common greenhouse gas, carbon dioxide. The molecular shape will be discussed and the concept of "global warming potential" (GWP) will be described. Historical data for carbon dioxide will be presented; trends and predictions will be made. Students will than be asked to apply these principles to a gas other than carbon dioxide.
Chemical concepts and content:
- molecular connectivity (Lewis structures)
- 3D structure (VSEPR)
- dipole moments
- Quantitative literacy
- definition of "global warming potential")
- data fitting
- data projection
Context for Use
This activity is designed to be used in a general chemistry class (1st or 2nd yr students). Ideally, students should be divided into groups of 3-4 students, with each group having access to a computer with internet access. It should be possible to complete the excercise in one class period, though it could be extended to a considerably longer period of time. (For example, rather than reporting back to the class during the class period, the groups could prepare written reports on their findings.) Students should be familiar with drawing Lewis structures of molecules, VSEPR, and determining the polarity of molecules. In addition, students should be familiar with software which allows graphing and fitting of functions to data (i.e. Excel).
Description and Teaching Materials
The teaching materials are data sets available at http://chemlinks.beloit.edu/Warming/index.html (Session 3: Greenhouse Gas Molecules) by G. C. Lisensky and S. C. Thorp. Extensions of this context to other topics in a typical General Chemistry course (e.g. balancing chemical equations, stoichiometric calculations) are available in the module cited above.
Assignment for Greenhouse Gas Exercise (Microsoft Word 47kB Jun9 10)
Teaching Notes and Tips
Students' understanding of this material may be determined through their ability to complete and explain the assigned exercise. They should be able to explain the basis of their projection into the future, address uncertainties in their calculations, and explain the physical basis for their trend continuing into the future. Students could be asked to address these questions in class, or to submit a written report on their conclusions.
References and Resources