Third Law of Thermodynamics - Thermodynamics and Statistical Mechanics - Lecture Slides, Slides of Thermodynamics

Download Third Law of Thermodynamics - Thermodynamics and Statistical Mechanics - Lecture Slides and more Slides Thermodynamics in PDF only on Docsity! Thermodynamics and Statistical Mechanics The Third Law of Thermodynamics Docsity.com Statements of Third Law •All reactions in a liquid or solid in thermal equilibrium take place with no change of entropy in the neighborhood of absolute zero. •(Nernst) •The entropy of a true equilibrium state of a system at absolute zero is zero. •(Planck) Docsity.com Nernst Postulate 0)(lim 0lim)(lim 0)(lim0)(lim slopes also ,0 As 210 12 0 12 0 00 =− =            ∂ ∂ −      ∂ ∂ =    ∂ −∂ =    ∂ ∆∂ =    ∂ ∆∂ ∆=∆→ → →→ →→ SS T G T G T GG T H T G HGT T PP T P T P T P T Docsity.com Planck This image cannot currently be displayed. 0lim lim so limlim and )(lim)(lim,0 As 0 0 00 00 =       ∂ ∂       ∂ ∂ =−       ∂ ∂ =      ∂ ∂ =→ → → →→ →→ S T G T GTHG T H T G THTGT T P T P P T P T TT Docsity.com Equivalence of Statements •Assume that the unattainability statement of the third law is valid, and show that it leads to the Nernst statement. •∆S0 = S01 – S02 = 0 Docsity.com Can Achieve T = 0 0 )( 2 12 12 0 2 0 101020 2 0 1010 202 00 = +−−= +=+ += ∫ ∫∫ ∫∫ ∫ ′T TT TT T T dTC T dTCSS T dTC T dTCS T dTCS T dTCSS Docsity.com Real Cooling Figure 10.4 Entropy- temperature diagram for an actual cooling process. The Sy unattainability of absolute zero is illustrated by the indefinitely increasing number of steps required to achieve a given temperature reduction as absolute zcro is approached. T Docsity.com Consequences of Third Law 0lim 0lim 1 = =      ∂ ∂       ∂ ∂ −=      ∂ ∂       ∂ ∂ = → → β β oT T oT TP P P S P S T V T V V Docsity.com