chem 211 7 notes - Thermodynamics (2nd and 3rd law) Entropy...

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Thermodynamics (2 nd and 3 rd law) Entropy Spontaneous change Spontaneous changes are changes that tend to occur w/o needing an external influence Does not necessarily take place rapidly Entropy and disorder Energy and matter tend to become more disordered Disorder is measured w/ entropy, S Low entropy means little disorder, large entropy means great disorder Second law of thermodynamics Natural progression of universe is to go from order to disorder rev q S T ∆ = q is energy transferred as heat, t is absolute temperature when change takes place rev means that energy must be transferred reversibly if a lot of energy is transferred to system, a lot of change in entropy entropy is a state function dependent on current state and independent of how that state was achieved changes in entropy heating increases thermal disorder positional disorder comes from disorder related to locations of molecues 2 1 ln( ) T S C T ∆ = (for changes in temperature), C is heat capacity of system 2 1 ln( ) V S nR V ∆ = for changes in volume 1 2 ln( ) P S nR P ∆ = for changes in pressure (NOTE p1/p2) entropy decreases when P2 >P1 entropy changes accompanying changes in physical state entropy increases as matter changes from solid --> liquid --> gas keep in mind these facts for changes in entropy 1. at transition temperature, temperature of substance remains constant as heat is supplied
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This note was uploaded on 08/17/2009 for the course CHEM 211 taught by Professor Crane, b during the Fall '06 term at Cornell University (Engineering School).

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chem 211 7 notes - Thermodynamics (2nd and 3rd law) Entropy...

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