Thomas Cox | Fri, 04/02/2021 - 22:30
The ideal gas law and gas stoichiometry problems are quite common from the high school chemistry classroom to the college general chemistry laboratory. But in reviewing common general chemistry textbooks (for example, Zumdahl & Zumdahls Chemistry and Tros Principles of Chemistry), gas stoichiometry as it applies to carbon dioxide production from a personal car or truck is missing. Many of my students are quite aware that carbon dioxide is a greenhouse gas and that CO2 is one of the main causes of concern for global warming and climate change. But when my general chemistry class reaches the topic of gas stoichiometry, I like to also bring into perspective the amount of carbon dioxide that is emitted or produced simply by driving their car and using 1 gallon of gasoline. The volume of CO2 is quite shocking!Concepts:atmospheric pressureclimate changecombustiongas lawsstoichiometryConcepts:
gas stoichiometry as applied to CO2emission from combustion of gasolineProcedure time:50 minutesPrep time:10 minutesMaterials:
Gas Stoichiometry Practice Problem:
When one gallon of gasoline (~2850g) is combusted in your car or truck, how many liters of gaseous CO2 are produced at a temperature of 20.5OC and pressure of 757mm Hg(l) (average daily temperature and pressure for Chico, California)?
Now let's bring this notion full circle: Wouldnt we expect carbon dioxide emissions to drop off or decline during the global pandemic? According to the International Energy Agency (IEA)1, the answer is yes but these declines have been short lived and the IEA reported that global carbon emissions were higher in December 2020 than December 2019. But it is worth noting that nearly half of these rapid changes in CO2 emissions are from transportation2. For example, carbon emissions and smog in California dropped off steeply at the onset of the pandemic in April 20203. But by the following autumn, car traffic in California had rebounded to roughly 90% of where it had been pre-pandemic (likely due to the delivery of food, groceries, and other goods)3.And with the large-scale production of several vaccines, it appears that there may be light at the end of the tunnel in terms of tackling the global COVID-19 pandemic; yet, when we reach the end of the pandemic tunnel, the issue of overwhelming CO2 emissions and a rapidly changing climate will still persist.
1https://www.iea.org/articles/global-energy-review-co2-emissions-in-2020. Accessed March 28, 2021.
2 Le Quéré, C., Jackson, R.B., Jones, M.W. et al. Temporary reduction in daily global CO2 emissions during the COVID-19 forced confinement. Nat. Clim. Chang. 10, 647653 (2020). https://doi.org/10.1038/s41558-020-0797-x
3https://roadecology.ucdavis.edu/files/content/projects/COVID_CHIPs_Impac... . Accessed March 29, 2021.Background:
scratch paper, calculator, a 1-liter bottleProcedure:
Provide students with the initial question and balanced chemical equation and allow them 5-10 minutes to attempt the problem on their own or in groups:
Then go over the solution together as a class and then discuss the implications of the solution. I find this goes really well with an open discussion among the class.Preparation:
Allow for anywhere between 20-50 minutes for this activity, depending on how much time allowed for students to work on this problem before going over the solution as well as how much time spent on the class discussion of the resultsAttribution:
Created and developed by the author Tom CoxCollection:Consumer ChemistryGasesMole and Quantifying MatterStoichiometry
Science Practice: Analyzing and Interpreting Data
Analyzing data in 912 builds on K8 and progresses to introducing more detailed statistical analysis, the comparison of data sets for consistency, and the use of models to generate and analyze data.Summary:
Analyzing data in 912 builds on K8 and progresses to introducing more detailed statistical analysis, the comparison of data sets for consistency, and the use of models to generate and analyze data. Analyze data using tools, technologies, and/or models (e.g., computational, mathematical) in order to make valid and reliable scientific claims or determine an optimal design solution.Assessment Boundary:Clarification:Links:NextGenerationScience.org
Science Practice: Asking Questions and Defining Problems
Asking questions and defining problems in grades 912 builds from grades K8 experiences and progresses to formulating, refining, and evaluating empirically testable questions and design problems using models and simulations.Summary:
Asking questions and defining problems in grades 912 builds from grades K8 experiences and progresses to formulating, refining, and evaluating empirically testable questions and design problems using models and simulations.
questions that challenge the premise(s) of an argument, the interpretation of a data set, or the suitability of a design.Assessment Boundary:Clarification:
Scientific questions arise in a variety of ways. They can be driven by curiosity about the world (e.g., Why is the sky blue?). They can be inspired by a models or theorys predictions or by attempts to extend or refine a model or theory (e.g., How does the particle model of matter explain the incompressibility of liquids?). Or they can result from the need to provide better solutions to a problem. For example, the question of why it is impossible to siphon water above a height of 32 feet led Evangelista Torricelli (17th-century inventor of the barometer) to his discoveries about the atmosphere and the identification of a vacuum.
Questions are also important in engineering. Engineers must be able to ask probing questions in order to define an engineering problem. For example, they may ask: What is the need or desire that underlies the problem? What are the criteria (specifications) for a successful solution? What are the constraints? Other questions arise when generating possible solutions: Will this solution meet the design criteria? Can two or more ideas be combined to produce a better solution?Links:NextGenerationScience.org
Related:environmental chemistrycombustioncombustion stoichiometryChemistry
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Thomas CoxButte College, Oroville, CaliforniaTommy, like an electron, but almost always in an "excited state"
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drive up windows
Donna Carter | Tue, 06/01/2021 - 13:16
Great way to make students aware of the hazards and implications of idling engines at the drive up windows.
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