大学物理(热学).ppt

2023/3/19,1,大学物理（热学）,ReviewExamplesOrder and Disorder,e=W/QH=1-QL/QH=1-TL/TH,Clausius deduction(1865),QL/TL=QH/TH,QH/TH-QL/TL=0,(Q/T)=0,T1,T2,T3,T4,T5,T6,T7,(Q1/T1+Q2/T2)+(-Q2/T2+Q3/T3)+(-Q6/T6+Q7/T7)=0,Irreversible:e=W/QH=1-QL/QH 1-TL/TH,QL/TLQH/TH,(Q/T)0,R&IR,For isolated system:S 0,“The energy of the universe is a constant.The entropy of the universe approaches a maximum.”,Clausius Statement,Entropy change in melting.A 1.00-kg piece of ice at 0oC melts very slowly to water at 0oC.Assume the ice in contact with a heat reservoir whose temperature is only infinitesimally greater than 0oC.Determine the entropy change of(a)the ice cube and(b)the heat reservoir.,Example 20-6,Entropy change when mixing water.A sample of 50.0 kg of water at 20.0oC is mixed with 50.0 kg of water at 24.0oC.Estimate the change in entropy without using calculus.,Example 20-7,Entropy changes in a free expansion.Consider the adiabatic free expansion of n moles of an ideal gas from volume V1 to volume V2,where V2 V1.Calculate the change in entropy(a)of the gas and(b)of the surrounding environment.(c)Evaluate S for 1.00 mole,with V2=2.00 V1.,Example 20-8,“Natural processes tend to move toward a state of greater disorder.”,Second Law,等几率假定,S=kBlnW,