Three Gas Laws in SCH3U

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Three Gas Laws in SCH3U

• Presenter Joy McCourt
• Mentor Nick Fox

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Aaaaahh, Gas Laws

• Dont they just make you feel like
• SINGING???

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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

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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.

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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 Boyles law, Charless law,
  Gay-Lussacs law, the combined gas law, Daltons
  law of partial pressures, and the ideal gas law
  AI

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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 Daltons law of partial pressures,
  Boyles law, Charless law, Gay-Lussacs law, the
  combined gas law, and the ideal gas law

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Position of Unit in Course

• What are the pros and cons of starting the course
  with the gas laws unit?

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Position of Unit in Course

• My rationale for trying it this way last year
• STAO ScienceWorks workshop on SCH3Usuccessfully
  used by others
• realistic picture of the course at the
  beginningmath and logic are required! ( gets a
  hard unit out of the way)

at STAO conference in November 2006
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Position of Unit in Course

• more gas in bigger balloon makes sense to
  studentsvery natural introduction to the mole
• Avogadros hypothesis arose from studying
  gas-state reactions.
• Worked for me.
• Your mileage may vary.

(This picture should bother you)
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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

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Position of Concepts in Unit

• States of Matter (how particle speed, types of
  motion, forces between particles affect their
  properties)
• How pressure affects volume (Boyles Law)
• How temperature affects volume and pressure
  (Charles Law, Gay-Lussacs Law)

or, in Nelson, the pressure-temperature law
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Position of Concepts in Unit

• The combined gas law (easy)
• Daltons Law (hard?) composition of the
  atmosphere (later in some texts)

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Position of Concepts in Unit

• How the amount of gas affects volume, pressure,
  and temperature (the ideal gas lawand 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.
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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.

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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 Boyles Law (tomorrows
  workshop)

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Hands-On Possibilities

• Purchase various sets of apparatus available on
  the market

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Hands-On Possibilities
For overhead use
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Suggested Lesson Sequence

• (refer to handout)

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Societal Applications

• Gas cylinder safety (helium tanks, welding
  equipment, etc.)
• Compressed Gas Cylinder Training Video - Missile
  Hazard
• (http//www.youtube.com/watch?vpe9gYRXQTTY)
• MythBusters
• (http//www.youtube.com/watch?vejEJGNLTo84)
• Occupations and situations that use compressed
  gases (anesthesia, water treatment, etc.)

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Societal Applications

• Popcorn, and some aspects of rising dough
• Hot air ballooning
• The bends (diving)

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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

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Misconceptions andStudent Difficulties

• Difficulty Gay-Lussacs Law
• or rather, getting past its name.

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Misconceptions andStudent Difficulties

• Solutions
• Model not being tripped up by its name.
• If discomfort arises, make sensitive use of this
  teachable moment.

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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).

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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.

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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?

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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.

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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/g
  lp.htm

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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.

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Misconceptions andStudent Difficulties

• Solution
• Patience, modeling, practice.
• opposite operations PV means the P is
  multiplying the Vmust divide both sides by P to
  get V.
• Build from easier examples can you solve 3x
  12?
• See students math teachers for any insight.

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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 gt P2, then
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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.

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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 theyve seen.

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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.

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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.

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Supporting Different Kindsof Learners

• Interpersonal learners also talking through
  practice problems with a partner or the teacher
• Kinesthetic learners hands-on learning

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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.

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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.
• Todays intro was from
• http//www.youtube.com/watch?vHbb9dGmU0r0

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Supporting Different Kindsof Learners

• Naturalistic learners connections to everyday
  occurrences, such as popcorn and breathing
• Intrapersonal intelligencehow can these learners
  best be supported, other than by allowing them to
  work independently (a strategy that doesnt
  actually connect to self-knowledge)???

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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