Nov_14 - Entropy Change Macroscopic it would be very...

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Entropy Change - Macroscopic it would be very difficult to use S if you had to count arrangements in initial and final states a small change in entropy dS is defined as d S process = q reversible , process T the total entropy change, ΔS, is the sum of all the small changes in entropy for constant temperature processes S process = q reversible , process T
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Entropy of a Phase Change at a normal melting/boiling/sublimation point, the two phases are in equilibrium, therefore ∆Η ° phase change = q rev, phase change since phase changes occur at constant T and P S phase change = q rev , phase change T phase change = H ˚ phase change T phasechange
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S for Phase Change - Example The vap for diethyl ether is 27.2 kJ/mol at its normal boiling point of 308 K. What is S vap for one mole of diethyl ether? S vap = q rev ,vap T vap = H ˚ vap T vap = 27,200J/mol 308 K = 88.3 J K 1
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2nd Law of Thermodynamics any spontaneous process must increase S
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This note was uploaded on 01/20/2011 for the course CHEM 154 CHEM 154 taught by Professor Yang during the Spring '10 term at UBC.

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Nov_14 - Entropy Change Macroscopic it would be very...

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