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Gas Behavior: Not Just Laws, Its a Good Idea Eric Grunden Raleigh Charter High School NCSTANov. 11, 2011 Slide 2 I.Whats the point of all this? I.Teach more by teaching less. II.What? That sounds like Zen nonsense. What else is being presented now? II.What am I going to learn from this? I.Something to help your students really get gas behavior II.Inquiry activities III.High cognitive level instruction ideas III.Do I get free stuff? I.Maybe. While hes talking, watch this movie of a crab being pushed into an underwater pipe by a pressure gradient. Slide 3 DONT TEACH THE GAS LAWS. Really. Slide 4 DONT TEACH THE GAS LAWS. Really. I.Too much memorizing without understanding. II.Too much work for you as a teacher. III.Too much stuff to learn IV.Emphasizes names V.Can be wrong Robert Boyle Im sceptical of this. (but then, my Facebook page is run by the Institute for Creation Research) Je suis Joseph Gay-Lussac! Je suis Jacques Charles! Je suis Guillaume Amontons! Qui? Slide 5 The Kinetic Theory of Gases A.Build a mechanical understanding of gas behavior. 1.Have students build a kinetic theory from observation. 2.Observe the simulation, note behaviors, and combine results, looking for the common observations. B.All gas behavior can be described from the 5 principles 1.Gas particle volume is insignificant 2.Particles move in constant, random, straight-line motion 3.Speed is proportional to temperature 4.Collisions are elastic 5.No forces act between particles Better Living through Simulations Slide 6 How much space is between molecules? These peanut butter cups would be 242 meters apart if they were He atoms at room temperature. (radius of a He atom: 31 pm; 3nm between He atoms at room temperature) Slide 7 Describe the four measurable characteristics of gases: Pressure: collisions with container walls (how hard, how often) Volume: distance traveled by particles Temperature: kinetic energy of particles (speed, as long as not comparing different gases) Number of particles: well, the number of particles This is a good time for sketching! This is a good time for small groups discussing effects of changing these conditions All explanations MUST BE in terms of molecular motion, not a gas law. Slide 8 OK, I lied. Teach ONE gas law: PV = nRT (For fun you can introduce non-ideal gases.) Slide 9 The important thing is to Build the mechanical understanding of simple gas behaviors Then APPLY that knowledge. 1.Prove the named gas laws 2.Find the molecular weight of butane 3.Jobs Method Student gas law projects Slide 10 The best gas demo material ever: 1.Balloon-filling 2.Stoichiometry 3.Demonstrating the Greenhouse Effect