第三章 : 统计热力学基础
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Transcript of 第三章 : 统计热力学基础
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:
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:::-::::
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: :()()() (): ()():
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.1:2:,
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1.:,,,,,.2.:, .
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localized system
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non-localized system
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. ... ..
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.UVNi
N1, N2, , Ni
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(3.1) (3.2) (3.3)(3.4)(3.4),tmtm
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N(3.5),,,: (3.5)(3.6):1., . 2.(3.6) ,.
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. : *i =N(3.6)(3.7)(3.7)
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:S=kN=ktm,(3.6)(3.7):S=kNi-ku (3.8)(UN),S(NUV),(3.8),S[NU(UV)]N,:(3.8):
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:dU=TdS-PdV,1/T: =-1/kT (3.9)(3.7): (3.10)(3.9)(3.8): S=kN-i/kT+U/T(3.11)
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F=U-TS=-NkT-i/kT : (3.11)(3.12) ,i ,F(T VN),(3.12) F.(3.12)
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.1.,,.:
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nx,ny,nzx,y,zgi=1nx ny nz1 1 2 1 2 12 1 1 gi=3
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(3.13):
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UVN(3.14)tm,
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,Nitm,Ni*,S,F: S=kNgi-i/kT +U/T (3.16) F=-NkTgi-i/kT (3.17) (3.15)
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2. (3.14)N!.(3.18),, Ni*,S,F: (3.18)N,:
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(3.20) SF (3.19)(3.21)
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. ,,:1.,(3.19):(3.22)
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2.0N0,(3.21): Ni=N0-i/kT (3.23)i=i-0i.,.,: P=P0-mgh/kT (3.24)Ph,P0(h=0),g,m,(3.23)0hT.
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.,:(1),,.(2),,,...,(3.13):
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,.NiNi,tt,NiNi+Ni,tt+t, (t+t)=NN-N+(Ni+Ni)gi --(Ni+Ni)(Ni+Ni)+(Ni+Ni) (3.26)(3.26)(3.25)::
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Ni,,N,Ni=0.,t. t=0: (1+x)=x-x2/2+x3/3-
(3.27)
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(3.28): :(3.28),,tm(tm+t).Ni,.
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,. 1%, ,, () ,? (3.28) Ni=3*1019.cm-3,Ni/Ni=0.01 : :
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,Ni,.tm,.,,.. U,V,N,,.t.,,P: P=/(a)
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(a),(b)..tx,: Px=tx/,,.,.: P=1/(b)
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. . U,V,N,1,2,,ig1,g2,,gi,:N1,N2,,Ni
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(t1):(3.29)(3.31)(3.30): (3.30),.,:
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(3.31)(3.32): S=k{gi(1+Ni*/gi)+ Ni*(1+gi/Ni*)} (3.33):,,.(3.32)
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.,,,,.iNigi,giNi,,,.giNi:
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,::(3.34)(3.35)
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:(3.36),: S=k{Ni*(gi/Ni*-1)-gi(1-Ni*/gi)} (3.38).(3.37)
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::+1,giNi, gi/Ni ,:::
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...
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e --i -1e --ie --i +1
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Boltzmann. : 1.,gie -i/kT .(3.39)
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2. ,.3.,,q ,.:(3.41),q . (3.39):(3.40)(3.41)
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1.(N) HelmholzF S(3.42)
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: (3.43)(3.20): (3.44)
3U(3.45)
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4GibbsGdF=-SdT-PdV,G=F+pV,(3.46)(5)H(3.47)
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(6)CV(3.48) 2. ,
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F()=-kTq(3.49)(3.50)(3.51)(3.52)
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(3.53)(3.54): ,U,H,CV, F,S,G. .
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.(r )(v )(e )(n )
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i(3.55)4.2*10-21,r(42-420)J/mol,v(4.2-42)kJ/mol, e, n.
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(3.56)
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(3.57)=qt*q():qt,qr,qV,qe,qn , ,,, .qq=gexp(-i/kT)i.
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: ,: F()= -NkTq =-NkTqt -NkTqr -NkTqv -NkTqe -NkTqn = Ft+Fr+Fv+Fe+Fn (3.58) : F()= -kTqN/N! = -kTqtN/N! -NkTqr -NkTqv -NkTqe -NkTqn
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:, kTN!,.= Ft+Fr+Fv+Fe+Fn (3.59)
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......
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.
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(3.60)(3.61) sn
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,.:1.,, (3.45)(3.47)(3.48)(),qn, .,,
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[(3.42)(3.43)(3.44)(3.46) ],qn.:
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. 2., , qn,, qn . .3.,.
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e,1-e,0=400kJ/moF, Cl ,:, -j+(2j+1), (2j+1).
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j,,:Ue=He=Cve=0 (3.62)Fe=-NkTqe (3.63)Ge=-NkTqe (3.64)Se=Nkqe (3.65)
:,, ,qe . .
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.1.ma*b*c(3.66)h, 1,2
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(3.67)(3.68)
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0gitqt,
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(3.69)
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2.1Helmholtz
2(3.70)
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(3.71)(Sackur-Tetrode),.,:
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(3) U=F+TS (3.72)4(3.73)
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5GibbsP=-(F/V)T,NUt,Ft
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. , ,,.1.(F): (3.21), F=-kTqN/N! =(N0n+N0e)-NkTg0ng0e-NkT(2mkT)3/2/h3 -NkTV+NkTN-NkT (3.74)
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..,,.
2.: S=-(F/T)V,N =Nk[g0ng0e+(2mk/h2)3/2+V-N +(3/2)T+5/2] (3.75) , .
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3. U=NkT2(q/T)V,N=(3/2)NkT (3.76) 4.CV CV=(U/T)V,N=(3/2)Nk (3.77)5.: =(F/N)T,V =(0n+0e) -kTg0ng0e -kT(2kT)3/2/h3 -kTkT + kTp (V=NkT/p) (3.78)
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,N=L,: =L (0n+0e)-RTg0ng0e -RT(2kT)3/2/h3 -RTkT+ RTp (3.79)
p,:
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,, (T),(3.78)(3.79),: = (T) + RTp/p (3.81)6.: p=-(F/V)T,N=NkT/V (3.82) .
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.qr qr
1 qr JIm1,m2 r
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(3.83)
- :r qr Ir H2 r,r /T
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2qr(360o (3.85)(3.86)
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3qr.1.vgi,v=1(3.87)
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vv=0,v,0 (3.87)
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Qv=hv/k,Qv,,,Qv,qv (3.88)
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, v,0=(1/2)hv=0,2.ft, frn(3.90)
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qv qv(3n-5) (3n-6)3.(3.91)
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I v j
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1HelmholtzFr,Fv2Sr=-(Fr/T)v,NSv=-(Fv/T)v,N(3.92)(3.93)(3.94)(3.95)
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3Ur,Uv4CV,r,CV,v(3.96)(3.97)
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(3.99)
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H G .(3.100)
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298.15 K1 molO2(g)Vgn,o=3,n,o=0,O2r=1.207*10-10mqnqv
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O2qe,qrqt
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khO2=2,
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Sm,tSackur-TetrodeNk=R,
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.,(1/2)kT,(1/2)kT.,:=3* [(1/2)kT+ (1/2)kT]=3kT,U=L*3kT=3RT,:Cv,m=-(U/T)v=3R=24.94J/(k*mol)(3.101)
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.:1..2..3.. 3.,N,3N. :qv=giv e-(v+)h/kT
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3N,:=(3/2)Nh+3NkT(1-e -h/kT)3N(3.102)(3.103)
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U=F+TS =(3/2)Nh+3Nh:S,F,Uv,,,,.:, Cv,(3.104)(3.105)
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(3.105),h/kT=v/T =X,N=L,:(3.106)XX/(ex-1)1/(ex-1)2.:(1) : X=v/T 0,ex1+x,Cv,m3R(1+v/T)3R
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(2) 0k: v>>T ,X(3),,:(3.107)
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:Cv,m=233.702R(T/D) =*TD,D=hm/k, m. (3.108)(3.109)(3.110)
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q=giexp(-i/kT)= qnqeqtqrqv(3.111)
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1.q=*2.q=**(3.112)(3.113)
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3.q=** 4.(3.114)
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,,,..F=-kTqNF=-kT()()(3.115)