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CHEM 433 - 9/23/10. III. A. 1st Law of Thermodynamics ( Chapter 2 ) - 1st Law of THERMO ( 2.2 ) - Expansion Work (2.3) READ: Chapter #2 (Exam W – review sometime M or T?). Work: dw = –Fdz
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CHEM 433 - 9/23/10 III. A. 1st Law of Thermodynamics (Chapter 2) - 1st Law of THERMO (2.2) - Expansion Work (2.3) READ: Chapter #2 (Exam W – review sometime M or T?)
Work: dw = –Fdz (A fancy way to say W = Force x distance… and that we have to integrate it if F changes over that distance)
Constant Pressure Expansion… w = –pextV An indicator diagram = A graph of p(V), which displays work as the a “area under the curve”
Isothermal Reversible Expansion… w = –nRTln(V2/V1) An isotherm More work in this case: reversible system is pushing against maximum possible pressure… Work for constant pressure case: w=-pextV