Entropy units, definition

The unit of entropy is indirectly determined by the stipulation above [Eq. (3.6)] and our definition for T. The unit for energy is called Joule (J), and the temperature unit Kelvin (K), resulting in the entropy unit Joule/Kelvin (J K ). This is exactly the... 

We define to be AH/(l/2 + AS )R. Since the numerator of this definition is an enthalpy and the denominator an entropy, must have the units of a temperature ... 

The configurational entropy per occupied lattice site (i.e., per unit mass rather than per unit volume) is by definition a monotonic function of temperature, and, of course, the fluid entropy deduced from calorimetric measurements also has this monotonic property. Figure 5a compares the mass and site configurational entropies computed from the LCT as functions of temperature T for the F-F and... 

The translational partition function is a function of both temperature and volume. However, none of the other partition functions have a volume dependence. It is thus convenient to eliminate the volume dependence of 5trans by agreeing to report values that use exclusively some volume that has been agreed upon by convention. The choices of the numerical value of V and its associated units define a standard state (or, more accurately, they contribute to an overall definition that may be considerably more detailed, as described further below). The most typical standard state used in theoretical calculations of entropies of translation is the volume occupied by one mole of ideal gas at 298 K and 1 atm pressure, namely, y° = 24.5 L. 

In this tribute and memorial to Per-Olov Lowdin we discuss and review the extension of Quantum Mechanics to so-called open dissipative systems via complex deformation techniques of both Hamiltonian and Liouvillian dynamics. The review also covers briefly the emergence of time scales, the definition of the quasibosonic pair entropy as well as the precise quantization relation between the temperature and the phenomenological relaxation time. The issue of microscopic selforganization is approached through the formation of certain units identified as classical Jordan blocks appearing naturally in the generalised dynamical picture. 

The Effect of Collisions on the Entropy.—Equation (1.6) represents the first part of our derivation of the effect of collisions in producing an irreversible change in the distribution and hence in increasing the entropy. Now we must go back to the definition of the entropy in Eq. (2.12) in Chap. V, and find how much S changes per unit time on account of the collisions. Differentiating that equation with respect to the time, we have at once... 

The science of thermodynamics has evolved from the mathematical treatment of common observations related to heat and work. The terms thus evolved have primarily mathematical definition and to find physical significance have been a somewhat tortuous process. We have seen that Entropy, which is the mathematical ratio of energy per unit absolute temperature, has been found to represent the extent of disorder. 

We can thus determine the entropy of a perfect gas, apart from the arbitrary constant as a function of the temperature T and the molecular volume v. The constant S is the entropy of the gas at the temperature T— and the volume v=. Its numerical value is therefore dependent on the units in which we measure temperature and volume. For a given system of units S has a definite value, like the molecular weight, for each gas. It is therefore a constant characteristic of the substance, and cannot be calculated by thermodynamics. ... 

The heats and entropies of fusion per mole of monomeric unit can vary over wide limits (Table 10-6). However, the entropy of fusion per mole of chain unit is moderately constant for many polymers. Since the melting point is essentially determined by the enthalpy of fusion, it was presumed that the cohesive energy is the definitive quantity. 

---