151F09_W2_LV_short

151F09_W2_LV_short - General Chemistry CHEM 151 Week 2 UA...

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UA GenChem General Chemistry General Chemistry CHEM 151 CHEM 151 Week 2
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UA GenChem Analysis What is this? Modeling How do I explain it? Synthesis How do I make it? Three central goals Why do substances undergo phase transitions with changing temperature or pressure? How do we MODEL these systems to Explain/Predict their behavior? Modeling Macroscopic Microscopic or Particulate Symbolic NaCl Three different perspectives
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UA GenChem Macro vs Micro Macroscopic Description We measure properties: Temperature ( T ) Pressure ( P ) Volume ( V ) Melting Point ( T m ) We observe things like Color State of Matter Reactivity Microscopic Description We model systems as composed by particles: Number ( N ) Mass ( m ) Speed ( v ) Kinetic Energy ( KE ) Potential Energy ( PE ) The challenge: Use microscopic descriptions to explain macroscopic behavior
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UA GenChem Solid Liqui d Gas A Particulate Model of Matter Basic Assumptions : Particles could represent anything we want: atoms, molecules, ions. Note : These representations are static , have unrealistic proportions , represent particles as solid objects . 1. Any macroscopic sample of a substance is composed of a large number of particles ;
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UA GenChem A Particulate Model of Matter Basic Assumptions: 2. Particles are constantly moving (translation, rotation, vibration); How do we explain pressure ” in microscopic terms? Pressure = Collision force/area of wall (intensive) Depends on: Volume , particle speed , mass number of particles
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UA GenChem Let’s look at a particle simulator Google “Ideal Gas Simulator” pick the one from OK State. http://www.chem.arizona.edu/chemdem/gaslaw Discovery Activity
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UA GenChem Look at the speed of the particles What do you notice about the SPEED of the particles? Do they all have the same speed? Do they have different speeds?
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UA GenChem Speed of ONE particle What do you notice about the SPEED of a single particle with no interference? Does it stay the same speed? Does it change speed as it goes?
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GenChem Particle Collisions What happens when two particles COLLIDE ? Do they retain the same speed?
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This note was uploaded on 02/06/2012 for the course CHEM 151 taught by Professor Staff during the Fall '08 term at Arizona.

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151F09_W2_LV_short - General Chemistry CHEM 151 Week 2 UA...

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