Thermodynamic Third Law

The energy-time uncertainty principle a purely dynamic (not thermodynamic) Third-Law limitation under quantum mechanics... 

Basic thermodynamics, statistical thermodynamics, third-law entropies, phase transitions, mixtures and solutions, electrochemical systems, surfaces, gravitation, electrostatic and magnetic fields. (In some ways the 3rd and 4th editions (1957 and 1960) are preferable, being less idiosyncratic.)... 

As we have seen, the third law of thermodynamics is closely tied to a statistical view of entropy. It is hard to discuss its implications from the exclusively macroscopic view of classical themiodynamics, but the problems become almost trivial when the molecular view of statistical themiodynamics is introduced. Guggenlieim (1949) has noted that the usefiihiess of a molecular view is not unique to the situation of substances at low temperatures, that there are other limiting situations where molecular ideas are helpfid in interpreting general experimental results ... 

A careful analysis of the fundamentals of classical thermodynamics, using the Born-Caratheodory approach. Emphasis on constraints, chemical potentials. Discussion of difficulties with the third law. Few applications. 

From the third law of thermodynamics, the entiopy 5 = 0 at 0 K makes it possible to calculate S at any temperature from statistical thermodynamics within the hamionic oscillator approximation (Maczek, 1998). From this, A5 of formation can be found, leading to A/G and the equilibrium constant of any reaction at 298 K for which the algebraic sum of AyG for all of the constituents is known. A detailed knowledge of A5, which we already have, leads to /Gq at any temperature. Variation in pressure on a reacting system can also be handled by classical thermodynamic methods. 

Because the third law of thermodynamics requires S = 0 at absolute zero, the following equation is derived, which enables the determination of the absolute value of the Seebeck coefficient for a material without the added complication of a second conductor ... 

The third law of thermodynamics states that the entropy of any crystalline, perfectly ordered substance must approach zero as the temperature approaches 0 K, and at T = 0 K entropy is exactly zero. Based on this, it is possible to establish a quantitative, absolute entropy scale for any substance as... 

These effects are shown in Figure 17.4, where the entropy of ammonia, NH3> is plotted versus temperature. Note that the entropy of solid ammonia at 0 K is zero. This reflects the fact that molecules are completely ordered in the solid state at this temperature there is no randomness whatsoever. More generally, the third law of thermodynamics tells us that a completely ordered pure crystalline solid has an entropy of zero at 0 K. 

Third law of thermodynamics A natural law that states that the entropy of a perfectly ordered, pure crystalline solid is 0 at 0 K Thomson, J. J., 25 Three Mile Island, 525-526 Threonine, 622t Tin... 

Unlike U for which there is no absolute base for energy, there is a state of complete order in which W is equal to one and therefore, S is equal to zero. Thus, absolute values of S can be determined. The procedure for doing so is the subject of the Third Law of Thermodynamics described in a later chapter. 

In the previous chapter, we saw that entropy is the subject of the Second Law of Thermodynamics, and that the Second Law enabled us to calculate changes in entropy AS. Another important generalization concerning entropy is known as the Third Law of Thermodynamics. It states that ... 

Experience indicates that the Third Law of Thermodynamics not only predicts that So — 0, but produces a potential to drive a substance to zero entropy at 0 Kelvin. Cooling a gas causes it to successively become more ordered. Phase changes to liquid and solid increase the order. Cooling through equilibrium solid phase transitions invariably results in evolution of heat and a decrease in entropy. A number of solids are disordered at higher temperatures, but the disorder decreases with cooling until perfect order is obtained. Exceptions are... 

Values for the thermodynamic functions as a function of temperature for condensed phases are usually obtained from Third Law measurements. Values for ideal gases are usually calculated from the molecular parameters using the statistical mechanics procedures to be described in Chapter 10. In either... 

C. C. Stephenson and W. F. Giauque. "A Test of the Third Law of Thermodynamics by Means of Two Crystalline Forms of Phosphine. The Heat Capacity. Heat of Vaporization and Vapor Pressure of Phosphine. Entropy of the Gas". J. Chem. Phys.. 5. 149-158 (1937). 

G. E. Gibson and W. F. Giauque. "The Third Law of Thermodynamics. Evidence from the Specific Heats of Glycerol that the Entropy of a Glass Exceeds that of a Crystal at the Absolute Zero". J. Am. Chem. Soc.. 45. 93-104 (1923). 

K. S. Pitzer and L. V. Coulter. "The Heat Capacities. Entropies and Heats of Solution of Anhydrous Sodium Sulfate and of Sodium Sulfate Decahydrate. The Application of the Third Law of Thermodynamics to Hydrated Crystals". J. Am. Chem. Soc.. 60. 1310-1313 (1938). 

The entropy of formation is calculated from 5° values obtained from Third Law measurements (Chapter 4) or calculated from statistical thermodynamics (Chapter 10). The combination of AfS with Af// gives AfG. For example, for the reaction at 298.15 K... 

P10.5 The thermodynamic functions for solid, liquid, and gaseous carbonyl chloride (COCL) obtained from Third Law and statistical calculations... 

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