Absolute zero, thermodynamic

Amontons Guillaume A. (1663-1705) Fr. phys., concept of absolute zero thermodynamic temperature at which gas pressure vanishes, constructor of thermometers and barometers Ampere Marie Andre (1775-1836) Fr. phys., founder of electrodynamics (Ampere s Law), inventor of galvanometer (book Theorie des phenomenes electro-dynamiques 1826)... 

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 ... 

Absolute The temperature relative to absolute zero, expressed in Kelvin. Also called thermodynamic temperature. 

Carnot s research also made a major contribution to the second law of thermodynamics. Since the maximum efficiency of a Carnot engine is given by 1 -T( H, if the engine is to be 100 percent efficient (i.e., Cma = 1), Tc must equal zero. This led William Thomson (Lord Kelvin) to propose in 1848 that Tf must be the absolute zero of the temperature scale later known as the absolute scale or Kelvin scale. ... 

Thermodynamics is concerned with the relationship between heat energy and work and is based on two general laws, the 1st and 2nd laws of thermodynamics, which both deal with the interconversion of the different forms of energy. The 3rd law states that at the absolute zero of temperature the entropy of a perfect crystal is zero, and thus provides a method of determining absolute entropies. 

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). 

In formulating the third law of thermodynamics Nernst1 and Planck2 assumed that a given substance at the absolute zero would have the same... 

We have already stated that some defects are related to the entropy of the solid, and that a perfeet solid would violate the second law of thermodynamics. The 2nd law states that zero entropy is only possible at absolute zero temperature. However, most solids exist at temperatures far above absolute zero. Thus, most of the solids that we eneounter are defeet-solids. The defects are usually "point defeets", which are atomlstie... 

This is an expression of Nernst s postulate which may be stated as the entropy change in a reaction at absolute zero is zero. The above relationships were established on the basis of measurements on reactions involving completely ordered crystalline substances only. Extending Nernst s result, Planck stated that the entropy, S0, of any perfectly ordered crystalline substance at absolute zero should be zero. This is the statement of the third law of thermodynamics. The third law, therefore, provides a means of calculating the absolute value of the entropy of a substance at any temperature. The statement of the third law is confined to pure crystalline solids simply because it has been observed that entropies of solutions and supercooled liquids do not approach a value of zero on being cooled. 

The third law of thermodynamics states that the entropy of a perfect crystal is zero at a temperature of absolute zero. Although this law appears to have limited use for polymer scientists, it is the basis for our understanding of temperature. At absolute zero (-273.14 °C = 0 K), there is no disorder or molecular movement in a perfect crystal. One caveat must be introduced for the purist - there is atomic movement at absolute zero due to vibrational motion across the bonds - a situation mandated by quantum mechanical laws. Any disorder creates a temperature higher than absolute zero in the system under consideration. This is why absolute zero is so hard to reach experimentally ... 

The third law of thermodynamics, one version of which is as a system approaches absolute zero of temperature, all processes cease and the entropy of the system approaches a minimum value , is of little importance for biogenesis. It means that it is impossible to cool a system down to absolute zero (even via an infinite number of steps). 

In a perfect crystal at 0 K all atoms are ordered in a regular uniform way and the translational symmetry is therefore perfect. The entropy is thus zero. In order to become perfectly crystalline at absolute zero, the system in question must be able to explore its entire phase space the system must be in internal thermodynamic equilibrium. Thus the third law of thermodynamics does not apply to substances that are not in internal thermodynamic equilibrium, such as glasses and glassy crystals. Such non-ergodic states do have a finite entropy at the absolute zero, called zero-point entropy or residual entropy at 0 K. 

In a similar way, the Systeme Internationale has defined other common physicochemical variables. The SI unit of temperature T is the kelvin. We define the kelvin as 1/273.16th part of the thermodynamic temperature difference between absolute zero (see Section 1.4) and the triple point of water, i.e. the temperature at which liquid water is at equilibrium with solid water (ice) and gaseous water (steam) provided that the pressure is 610 Pa. 

Kelvin then replotted his data, this time extrapolating each graph till the volume of the gas was zero, which he found to occur at a temperature of -273.15 °C see Figure 1.5. He then devised a new temperature scale in which this, the coldest of temperatures, was the zero. He called it absolute zero, and each subsequent degree was equal to 1 °C. This new scale of temperature is now called the thermodynamic (or absolute) scale of temperature, and is also sometimes called the Kelvin scale. 

Statistical mechanics affords an accurate method to evaluate ArSP, provided that the necessary structural and spectroscopic parameters (moments of inertia, vibrational frequencies, electronic levels, and degeneracies) are known [1], As this computation implicitly assumes that the entropy of a perfect crystal is zero at the absolute zero, and this is one of the statements of the third law of thermodynamics, the procedure is called the third law method. 

The symbol 9 is called the characteristic temperamre and can be calculated from an experimental determination of the heat capacity at a low temperature. This equation has been very useful in the extrapolation of measured heat capacities [16] down to OK, particularly in connection with calculations of entropies from the third law of thermodynamics (see Chapter 11). Strictly speaking, the Debye equation was derived only for an isotropic elementary substance nevertheless, it is applicable to most compounds, particularly in the region close to absolute zero [17]. 

Lewis and Gibson [3] also emphasized the positive entropy of solutions at 0 K and pointed out that supercooled liquids, such as glasses, even when composed of a single element (such as sulfur), probably retain a positive entropy as the temperamre approaches absolute zero. For these reasons Lewis and Randall [4] proposed the following statement of the third law of thermodynamics ... 

From the third law of thermodynamics, it is possible to derive several limiting relationships for the values of thermodynamic quantities at absolute zero for perfect crystalline substances. 

With the development of statistical thermodynamics and the calculations of the entropies of many substances from spectroscopic data, several other substances in addition to hydrogen have been found to have values of molar entropies that disagree with those calculated from thermal data alone [13] (Table 11.1). The discrepancies can be accounted for on the assumption that even near absolute zero not all molecules are in the same state and that tme equilibrium has not been attained. For CO, COCI2, N2O, NO, and CIO3F, the close similarity in the sizes of the atoms makes different... 

Innate Thermodynamic Quantities. Certain components of the total change in AG° are innate, because such parameters have nonzero values, even when extrapolated to 0 K. Other components change with temperature e.g., at r = 0 K, TA = 0). Because A = U - TS and G = H - TS - then = Go°) = (Ao° = Uo°) at absolute zero. Except for entropy, the residual values of these quantities are the same at absolute zero, and they describe the innate thermodynamic behavior of the system. 

A unit of thermodynamic temperature (symbolized by K) that is one of the seven SI base units. The kelvin is equal to 1/(273.16) of the thermodynamic temperature of the triple point of water. (Note Absolute zero is 0 K, and not 0°K.)... 

Third Law of Thermodynamics. Also referred to as the Nernst heat theorem, this law states that it is impossible to reduce the temperature of any system, via a finite set of operations, to absolute zero. For any changes involving perfectly crystalline solids at absolute zero, the change in total entropy is zero (thus, A5qk = 0). A corollary to this statement is that every substance, at T > 0 K, must have a positive and finite entropy value. The entropy of that substance is zero only at absolute zero when that substance is in pure, perfect crystalline form. See Entropy... 

It is more problematical to define the third law of thermodynamics compared to the first and second laws. Experimental work by Richards (1902) and Nemst (1906) led Nemst to postulate that, as the temperature approached absolute zero, the entropy of the system would also approach zero. This led to a definition for the third law of thermodynamics that at a temperature of absolute zero the entropy of a condensed system would also be zero. This was further refined by Planck (1911) who suggested this be reworded as the entropy of a pure element or substance in a perfect crystalline form is zero at absolute zero. 

Readout of the ligand information by a substrate is achieved at the rates with which L and S associate and dissociate it is thus determined by the complexation dynamics. In a mixture of ligands Li, L2. .. L and substrates Si, S2. . - S , information readout may assume a relaxation behaviour towards the thermodynamically most stable state of the system. At the absolute zero temperature this state would contain only complementary LiSi, L2S2. .. L S pairs at any higher temperature this optimum complementarity state (with zero readout errors) will be scrambled into an equilibrium Boltzmann distribution, containing the corresponding readout errors (LWS , n n ), by the noise due to thermal agitation. 

The value of C should be zero at absolute zero temperature, which is required by the third law of thermodynamics, but the translational energy has a very small quantum step, so that it is fully activated even at very low temperatures, and C = iR/2 is the fully activated value. 

The third law of thermodynamics states that, for a perfect crystal at absolute zero temperature, the value of entropy is zero. The entropy of a molecule at other temperatures can be computed from the heat capacities and heats of phase changes using... 

The third law of thermodynamics says that the entropy of pure, perfect crystalline substance is zero at absolute zero. But, in actual practice, it has been found that certain chemical reactions between crystalline substance, do not have DS = 0 at 0°K, which indicates that exceptions to third law exist. Such exceptional reactions involve either ice, CO, N2O or H2. It means that in the crystalline state these substances do not have some definite value of entropy even at absolute zero. This entropy is known as Residual Entropy. At 0°K the residual entropies of some crystalline substances are... 

The maximum in susceptibility as a function of temperature can be explained using thermodynamic reasoning. At absolute zero, the spin moments are aligned as antiparallel as possible, yielding a small susceptibility. With increasing temperature, the tendency for disorder or more random alignment of spin moments become greater. 

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