Thermo & Stat Mech - Spring 2006 Class 10 1 Thermodynamics and Statistical Mechanics The Third Law of Thermodynamics

Thermo & Stat Mech - Spring 2006 Class 102 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)

Thermo & Stat Mech - Spring 2006 Class 103 Statements of Third Law It is impossible to reduce the temperature of a system to absolute zero using a finite number of processes. (Unattainability statement)

Thermo & Stat Mech - Spring 2006 Class 104 Entropy

Thermo & Stat Mech - Spring 2006 Class 105 Nernst Postulate

Thermo & Stat Mech - Spring 2006 Class 106 Planck

Thermo & Stat Mech - Spring 2006 Class 107 Equivalence of Statements Assume that the unattainability statement of the third law is valid, and show that it leads to the Nernst statement.  S 0 = S 01 – S 02 = 0

Thermo & Stat Mech - Spring 2006 Class 108 Equivalence of Statements Consider adiabatic cooling

Thermo & Stat Mech - Spring 2006 Class 109 Adiabatic Cooling Plot

Thermo & Stat Mech - Spring 2006 Class 1010 Can Achieve T = 0

Thermo & Stat Mech - Spring 2006 Class 1011 Real Cooling

Thermo & Stat Mech - Spring 2006 Class 1012 Consequences of Third Law

Thermo & Stat Mech - Spring 2006 Class 1013 Consequences of Third Law Clausius-Clapeyron equation

Thermo & Stat Mech - Spring 2006 Class 1014 Consequences of Third Law