Three Gas Laws in SCH3U

1. Three Gas Laws in SCH3U Presenter: Joy McCourt Mentor: Nick Fox

2. Aaaaahh, Gas Laws… Don’t they just make you feel like… …SINGING???

3. Outline • Curriculum Expectations • Position of Unit in Course; Position of Concepts in Unit • Hands-On Possibilities • Suggested Lesson Sequence • Societal Applications • Safety concerns • Misconceptions and Student Difficulties • Challenging/Supporting Different Levels of Classes • Supporting Different Kinds of Learners • References

4. Curriculum Expectations Overall: • F2. investigate gas laws that explain the behaviour of gases, and solve related problems; • F3. demonstrate an understanding of the laws that explain the behaviour of gases.

5. Curriculum Expectations Specific: Inquiry: • F2.2 determine, through inquiry, the quantitative and graphical relationships between the pressure, volume, and temperature of a gas [PR, AI] • F2.3 solve quantitative problems by performing calculations based on Boyle’s law, Charles’s law, Gay-Lussac’s law, the combined gas law, Dalton’s law of partial pressures, and the ideal gas law [AI]

6. Curriculum Expectations Knowledge and Understanding: • F3.4 describe, for an ideal gas, the quantitative relationships that exist between the variables of pressure, volume, temperature, and amount of substance • F3.5 explain Dalton’s law of partial pressures, Boyle’s law, Charles’s law, Gay-Lussac’s law, the combined gas law, and the ideal gas law

7. Position of Unit in Course What are the pros and cons of starting the course with the gas laws unit?

8. Position of Unit in Course My rationale for trying it this way last year: • STAO ScienceWorks workshop on SCH3U*—successfully used by others • realistic picture of the course at the beginning—math and logic are required! (& gets a hard unit out of the way) *at STAO conference in November 2006

9. Position of Unit in Course • “more gas in = bigger balloon” makes sense to students—very natural introduction to the mole • Avogadro’s hypothesis arose from studying gas-state reactions. Worked for me. Your mileage may vary. (This picture should bother you…)

10. Position of Concepts in Unit If you do start with this unit… • Introductory information: • Math basics: significant figures, rearranging equations • Using conversion factors: pressure unit conversions

11. Position of Concepts in Unit • States of Matter (how particle speed, types of motion, & forces between particles affect their properties) • How pressure affects volume (Boyle’s Law) • How temperature affects volume and pressure (Charles’ Law, Gay-Lussac’s Law*) *or, in Nelson, “the pressure-temperature law”

12. Position of Concepts in Unit • The combined gas law (easy) • Dalton’s Law (hard?); composition of the atmosphere (later in some texts)

13. Position of Concepts in Unit • How the amount of gas affects volume, pressure, and temperature (the ideal gas law…and the mole!) • Mass-volume connections (using “The Mole Highway” or “The Y Diagram”)—including “The SCH3U Lighter Lab”! (see posted Best Practice) • Overall STSE connection: air quality I address gas stoichiometry by coming back to these ideas as part of the unit on quantities in chemical reactions.

14. Hands-On Possibilities Play Time! Guided activities to come up with explanations / relationships between the variables involved... …qualitative experiences to associate with concepts and use to understand new situations.

15. Hands-On Possibilities Quantitative: • 2001 course text by McGraw-Hill Ryerson: • C-clamp, ruler + sealed plastic pipette  Boyles’ Law • Water bath, ruler, thermometer + sealed plastic pipette  Charles’ Law (similar, but more advanced, method in Rockley & Rockley (1995)) • Vernier probeware: Boyle’s Law (tomorrow’s workshop)

16. Hands-On Possibilities • Purchase various sets of apparatus available on the market

17. Hands-On Possibilities For overhead use:

18. Suggested Lesson Sequence • (refer to handout)

19. Societal Applications • Gas cylinder safety (helium tanks, welding equipment, etc.) • Compressed Gas Cylinder Training Video - Missile Hazard (http://www.youtube.com/watch?v=pe9gYRXQTTY) • MythBusters (http://www.youtube.com/watch?v=ejEJGNLTo84) • Occupations and situations that use compressed gases (anesthesia, water treatment, etc.)

20. Societal Applications • Popcorn, and some aspects of rising dough • Hot air ballooning • “The bends” (diving)

21. Speaking of Safety… • The main safety concerns when studying this unit have to do with: • Pressurized gases • High temperatures • Electrical safety when using hot plates and probes • Fire concerns when using Bunsen burners (e.g., to seal plastic pipettes) • Fumes created while sealing plastic pipettes • Taking care not to break thermometers

22. Misconceptions andStudent Difficulties • Difficulty: Gay-Lussac’s Law • …or rather, getting past its name.

23. Misconceptions andStudent Difficulties • Solutions: • Model not being tripped up by its name. • If discomfort arises, make sensitive use of this “teachable moment.”

24. Misconceptions andStudent Difficulties • Solutions: • 2002 Nelson textbook calls it “the pressure-temperature law.” Rationale: “history of science references say that Charles, Dalton and Gay-Lussac were all involved in investigating this relationship, with Charles and Dalton doing their work before Gay-Lussac” (p. 435). Considered for very immature classes (at the cost of some science history and an opportunity for dialogue).

25. Misconceptions andStudent Difficulties • Difficulty: Which law? / What kind of change? • From Horton (2007): “For example, Herbert Beall (1994) lectured college freshmen on the second law of thermodynamics and the ideal gas laws. After the lecture only 11% were able to correctly predict the effect that opening a cylinder of compressed gas would have on the temperature of the gas.”

26. Misconceptions andStudent Difficulties • Solution: • Hands-on examples -- “hooks” on which to hang the concepts and relate to new situations. • Practice examining units and descriptions for clues • GRASP method (see previous presentations): What are you given? What are you asked to find? Which equation relates those quantities?

27. Misconceptions andStudent Difficulties • Difficulty: visualizing the molecular level • Solution 1: put it in real-world terms. Example: Jumpy, energetic dancers dancing to fast-paced music vs. dancers doing a slow dance.

28. Misconceptions andStudent Difficulties • Solution 2: simulators (demo or worksheet-guided computer lab) • http://www.chem.ufl.edu/~itl/2045/MH_sims/gas_sim.html • http://intro.chem.okstate.edu/1314f00/laboratory/glp.htm

29. Misconceptions andStudent Difficulties • Difficulty rearranging equations • May know how to handle + / - but not × / ÷ • May not know how to handle + / - , either; may only solve for x by using guess-and-check.

30. Misconceptions andStudent Difficulties • Solution: • Patience, modeling, practice. • “opposite” operations: “PV” means the P is multiplying the V…must divide both sides by P to get V. • Build from easier examples: can you solve 3x = 12? • See student’s math teachers for any insight.

31. Challenging/SupportingDifferent Levels of Classes Ready for a Challenge • Take them through the full work-up of each law, including the use of proportionality constants Need More Support • Help them to connect what we expect in the real world and the form of the relevant equation; use ratios , so If P1 > P2, then…

32. Challenging/SupportingDifferent Levels of Classes Ready for a Challenge • Less scaffolding / fewer supports in questions • Expect more detailed explanations of the microscopic level • Expect them to explain why all three variables are actually involved in a situation Need More Support • Teach careful work through Predict-GRASP-Check or a similar strategy • Teach them to make a common-sense prediction first, then check their calculated answer against their prediction • Fewer questions / extra time.

33. Supporting Different Kindsof Learners • Visual/Spatial learners: • microscopic picture may be easier for them • again, check the reasonableness of answers by considering real-world examples they’ve seen.

34. Supporting Different Kindsof Learners • Linguistic intelligence: • Reading style: assigned readings from the text to consolidate in-class learning • Writing style: should summarize (in writing) readings and hands-on work; write notes/fill in blanks during lectures.

35. Supporting Different Kindsof Learners • Linguistic intelligence: • Auditory style: listen more and take notes less during lecture (but should take some) • Verbal: “talking through” practice problems with a partner or the teacher.

36. Supporting Different Kindsof Learners • Interpersonal learners: also “talking through” practice problems with a partner or the teacher • Kinesthetic learners: hands-on learning

37. Supporting Different Kindsof Learners • Logical-mathematical students: • will likely find the calculations easier than classmates • if not Visual, talk through the logic of the simulations with them until they can reason their way through microscopic situations.

38. Supporting Different Kindsof Learners • Musical: • Challenge them to write a song to remember the laws (but they can only sing it in their heads during quizzes ) • Allow musical final products in some assignments. Today’s intro was from http://www.youtube.com/watch?v=Hbb9dGmU0r0

39. Supporting Different Kindsof Learners • Naturalistic learners: connections to everyday occurrences, such as popcorn and breathing • Intrapersonal intelligence…how can these learners best be supported, other than by allowing them to work independently (a strategy that doesn’t actually connect to self-knowledge)???

40. References • Ontario Science curriculum (2008 revision) • STAO ScienceWorks SCH3U workshop • Horton, C. (2004). Student Misconceptions and Preconceptions in Chemistry. California Journal of Science Education, 7 (2), 1531-2488. • Jenkins, Frank, et al. (2002). Chemistry 11. Toronto: Nelson. • Mustoe, Frank, et al. (2001). Chemistry 11. Toronto: McGraw-Hill Ryerson. • Rockley, Natalie L. (1995). A Charles’ Law Experiment for Beginning Students. Journal of Chemical Education, 72 (2), 179-181