Heat Capacity, Incremental Enthalpy, Entropy

Thermodynamic functions (Cp=heat capacity, H = enthalpy, G = Gibbs free energy, S = entropy) for LaSe and NdSe listed below are based on estimated Cp data. Heat capacity measurements on LaSe in the range 90 to 400 K (see p. 76) have been extrapolated by employing one Debye function and one Einstein function. Selected values (in cal mor K except Hj-Hgee i cal/mol) are  

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The heat capacity of thiazole was determined by adiabatic calorimetry from 5 to 340 K by Goursot and Westrum (295,296). A glass-type transition occurs between 145 and 175°K. Melting occurs at 239.53°K (-33-62°C) with an enthalpy increment of 2292 cal mole and an entropy increment of 9-57 cal mole °K . Table 1-44 summarizes the variations as a function of temperature of the most important thermodynamic properties of thiazole molar heat capacity Cp, standard entropy S°, and Gibbs function - G°-H" )IT. 

There have been no experimental determinations reported on the heat capacity or enthalpy increments of ZrBr, ZrBr2 or ZrBr3. Values for these parameters and the corresponding entropies have been estimated by [97V1S/COR] such that reasonable trends are obtained when compared with the equivalent values of zirconium chloride and iodide values. The values for the heat capacities and entropies, at 298 K, estimated by [97VIS/COR] are, C (ZrBr, cr, 298.15 K) = (50 3) J-lC -moP, C , (ZrBrj, cr,... 

The general thermodynamic properties of proteins reported above give rise to several questions What do the asymptotic (at Tx) values of the denaturation enthalpy and entropy mean and why are they apparently universal for very different proteins Why should the denaturation enthalpy and entropy depend so much on temperature and consequently have negative values at low temperature In other words, why is the denaturation increment of the protein heat capacity so large, with a value such that the specific enthalpies and entropies of various proteins converge to the same values at high temperature ... 

The denaturational increment of the heat capacity might be described partly by the increase of the extent of configurational freedom of the protein molecule upon denaturation. However, as was shown by Sturte-vant (J977) and Velicelebi and Sturtevant (1979), the contribution of this effect to the observed denaturational increment of the protein heat capacity cannot be large. This conclusion becomes especially evident from the impossibility of using this configurational effect alone to explain the negative values of the enthalpy and entropy of protein denaturation at low temperatures. 

The JANAF Thermochemical Tables consist of thermal functions and formation functions, both of which are temperature dependent. The thermal functions consist of heat capacity, enthalpy increments, entropy, and Gibbs en-... 

The layout of the tables and the functions quoted correspond to conventions which are also used in standard works such as the JANAF Tables and the Tables of the U.S. Bureau of Mines. The following thermochemical functions are tabulated heat capacity Cp, entropy S, Gibbs energy function —Gef = - [C-//(298.15)1 / 7] enthalpy H, enthalpy increment //-//(298.15), Gibbs energy G = H-TS, and the formation quantities AH(,AG and logA f. The formation reactions refer to the reference states of the elements, which are given in a separate table. 

Subsequently, Huntelaar et al. [95HUN/COR] measured the heat capacity and related thermochemical properties of SrZrSi207(s). The heat capacity was measured between 10 and 320 K using adiabatic calorimetry whereas enthalpy increments relative to 298.15 K were determined between 400 and 850 K using drop calorimetry. After correction for a zirconia impurity and estimation of the heat capacity below 13 K using the function A.T (where A is 0.000251 J-moP ), the heat capacity and entropy at... 

A method to estimate thermochemical properties for radicals from the corresponding properties of the parent and of derivation of hydrogen bond increment (HBI) groups, is described by Lay et al. [25] and Sun and Bozzelli [133]. The method uses the bond energy (298.K) for loss of a hydrogen on the central atom for the enthalpy term, the difference between the radical and the parent for the heat capacity (Cp(T)) term and the intrinsic entropy difference for the term. 

TEMPERATURE VARIATION OF THE HEAT CAPACITY AT CONSTANT PRESSURE AND THE CALCULATION OF THERMODYNAMIC QUANTITIES. I. CALCULATION OF ENTROPY AND ENTHALPY INCREMENTS. //ENGLISH TRANSLATION OF ZHUR. FIZ. KHIM. 39 /6/ 1345-7,1965.//... 

Ideal gas values for the heat capacity, enthalpy increment, and entropy can be computed from the partition function Q. 

This is however a potential point of error (having a tendency to affect the computed entropy somewhat more visibly than the corresponding enthalpy increment or heat capacity), and the user is warned about this simplification, which is often used, for example, to convert OK enthalpy of formation to 298K value. 

Apart from standard molar enthalpies of formation Af T (r) of substances B (see Section 8), most commonly given at T = 298.15 K and at r -> 0, and standard molar entropies iS (3T) (see Section 9) and standard molar heat capacities C, b(T), each most commonly given at T = 298.15 K, other quantities found in thermodynamic tables include values of the increments in the standard molar enthalpies, especially... 

A limited number of low temperature heat capacity measurements have been described. The adiabatic calorimetric measurements of Westrum and Beale (1961) are the only data available for the trifluorides. Similar heat capacity measurements have recently been reported for the lighter lanthanide trichlorides (La-Gd) in the range 5-350 K (Sommers, 1976), and for EuBr3 in the range 5-340 K (Deline et al., 1975). Heat capacities, enthalpy and entropy increments... 

Gibbs energies, enthalpies, entropies, heat capacities, and volumes, as well as intensive properties, such as permitlivities or viscosities. The excess functions of extensive properties over those for ideal mixtures of the components, symbolized by y (or the respective increments for intensive quantities, symbolized by AT), are usually defined in terms of the mole fraction composition with respect to the pure components ... 

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