Third Law of Thermodynamics
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Third Law of Thermodynamics Walther Nernst (1864 – 1941) Nernst Postulate (Weak Form) The entropy change associated with any condense system undergoing a reversible isothermal proce approaches zero as temperature approaches 0 K, where condensed system refers to liquids and solids. Third Law of Thermodynamics No finite sequence of cyclic processes can succe cooling a body to absolute zero.
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Third Law of Thermodynamics. Third Law of Thermodynamics. No finite sequence of cyclic processes can succeed in cooling a body to absolute zero. Nernst Postulate (Weak Form). The entropy change associated with any condensed system undergoing a reversible isothermal process - PowerPoint PPT Presentation
Transcript of Third Law of Thermodynamics
Third Law of Thermodynamics
Walther Nernst(1864 – 1941)
Nernst Postulate (Weak Form)The entropy change associated with any condensedsystem undergoing a reversible isothermal processapproaches zero as temperature approaches 0 K, where condensed system refers to liquids andsolids.
Third Law of ThermodynamicsNo finite sequence of cyclic processes can succeed incooling a body to absolute zero.
Max Planck(1858-1947)
Nernst Postulate (Strong Form)The entropy of all perfectly crystalline substances iszero at absolute zero.
Boltzmann’s Interpretation
Tabulated ResultsFunction of Molecular Size
Species So(298) J/K mol Species So(298) J/K molLi 29.1 HF 173.7Na 51.4 HCl 186.8K 64.7 HBr 198.6Rb 69.5 HI 206.3Cs 85.2
Function of Molecular ComplexitySpecies So(298) J/K mol Species So(298) J/K molNO 211 CH4 186
NO2 246 C2H6 230
N2O4 304 C3H8 270
C4H10 310
Entropy of Substances
Residual Entropy
Ice I Structure Ice II Structure
