Tables of Thermodynamic Data

5 TABLES OF THERMODYNAMIC DATA 7.5a Reference States and State Properties 

A convenient way to tabulate measured changes in 0 or H is to choose a temperature, pressure, and state of aggregation as a reference state, and to list AO or AH for changes from this state to a series of other states. Suppose, for example, that the enthalpy changes for carbon monoxide going from a reference state of 0°C and 1 atm to two other states are measured, with the following results  

Some enthalpy tables give the reference states on which the listed values of H are based and others do not however, you do not have to know the reference state to calculate H for 

This convenient result is a consequence of the fact that //, like U, is a state property, or a property of a system component whose value depends only on the state of the system (temperature, pressure, phase, and composition) and not on how the system reached that stale. We will have more to say about this concept in Chapter Eight. 

The following entries are taken from a data table for saturated methyl chloride  

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For pure organic materials, it is also possible to calculate the heating value starting from the heats of formation found in tables of thermodynamic data. The NHV is obtained using the general relation of thermochemistry applicable to standard conditions of pressure and temperature (1 bar and 25°C)) f 9j... 

By use of Othmer plots of reference substances, large tables of thermodynamic data can be expressed as simple correlations which are extremely accurate and easy to use. The real power of these correlations is the abiUty to interpolate and extrapolate the correlations beyond the experimental values with considerable accuracy. Mathematically stated... 

Appendix 1 includes a review of SI base units as well as tables of thermodynamic data and equilibrium constants. 

This fundamentally important equation links thermodynamic quantities—which are widely available from tables of thermodynamic data—and the composition of a system at equilibrium. 

The column heading vZS refers to the results obtained by Van Zeggeren and Storey (1970) for the same system but using the JANAF tables of thermodynamic data. 

There are extensive tables of thermodynamic data which give standard enthalpies and free energies of formation and entropies in the standard... 

In Fig. 8 is shown a plot of the standard heats of solution of alkali halides (infinite dilution) against the difference between the absolute heats of hydration of the corresponding anion and cation. The values of q are from Table 3 of the present work and the values of Wx- and Wm.+ are those obtained by method 1 and hsted in col. 2 of Table 7. The graph tends to justify a basic assumption made by Vasil ev et al. [65) in the derivation of their table of thermodynamic data for hydration of individual ions, namely, that 1 08+ — Wi—... 

Tables of thermodynamic data necessary to apply equations listed by Cook are given in Appendix II of his book. The complete solution of the thermohydrodynamic theory for condensed explosives may then be effected in principle by a simultaneous solution of eqs...

Appendix C Tables of Thermodynamic Data Appendix D Glossary of Symbols... 

Using tables of thermodynamic data, it is possible to work out the energy differences for many different reactions at different temperatures. For example, for the combustion of isooctanc, AG° (at 298 K) = -1000 kj mol-1. 

To obtain A H B we look up the values of the separate formation enthalpies of reactants and products in tables of thermodynamic data. Then... 

For very hot flames (that is, Tb > 1500 K) such computations, which can be made from tables of thermodynamic data, can become extremely laborious, since no explicit equation for Tb can be written. Instead, Tb itself depends on the various equilibria among the product species at the temperatures concerned, the product species may include appreciable concentrations of free radicals. Such calculations are described by S. R. Brinkley, Jr., in Combustion Processes, vol. II, chap. C, Princeton University Press, Princeton, N.J., 1956. 

In the crown ethers (18) the interactions between the ligand and metal ion are considered to be more electrostatic in nature, rather than the covalent binding observed for the transition metal complexes of the aza, thia, and phospha macrocycles. The thermodynamic properties of these macrocycles have been extensively studied, with numerous reviews covering complexation, selectivity, and structural aspects, some with extensive tables of thermodynamic data. Considerable efforts have been made to correlate the interrelationship between cavity size of the macrocycles and stability of alkali and alkaline earth metal complexes. From X-ray and CPK models, cavity radii are determined as 0.86-0.92A for 15-crown-5 (64), 1.34-1.43 A for 18-crown-6 (65), and about 1.7 A for 21-crown-7 (66). For complex formation between the alkali metal ions and 18-crown-6, the maximum stability... 

D. L. Hildenbrand, "Tables of Thermodynamic Data for Performance Calculations, Newport Beach, Calif., September, 1959. 

UPAC has changed the standard pressure from I atm to I bar. Became I bar is equal to 0.981 atm, the differences in thermodynamic calculatiom are negligible except in -work of very high precision. Many tables of thermodynamic data are still based on a standard pressure of 1 atm, so we will me it in this book. 

In practice, G and H for a substance are defined relative to the G and H for the constituent elements. These relative values are known as free energy of formation and enthalpy of formation for standard conditions and referred to as AG° and AH°. Values for these functions may be obtained from standard tables of thermodynamic data, usually for the reference temperature of 298.2 K. The Chemical... 

Finally, although neither G nor H can be measured in absolute terms, so that we are forced always to use differences of these quantities, absolute values of S can be measured calorimetrically. Thus, tables of thermodynamic data for compound i contain values of A/G°, A fH°, and Sf, where S is the entropy of i. If we want a value of A fS°, we must calculate it from the tabulated values of S for the compound and its constituent elements. 

A typical table of thermodynamic data looks like Table 3.1. Note that A/H° and A fG° for the element Ca are both zero. This does not mean that Hfa = 0, or G a = 0. We don t know what these values are. A/G° = 0 just means that G ,a — G a = 0. 

Table 3.1. A typical table of thermodynamic data (NBS tables Wagman et al., 1982).

The Thermodynamics Research Center at Texas A M University (TRC) has assembled, collected, evaluated and published tables of thermodynamic data for nearly 60 years. These current volumes describing vapor pressures come from those tables and other evaluation projects conducted by TRC and other research groups, and, as of the publication date, represent all known, evaluated data. The volumes contain constants derived from fitting experimental data with the Antoine and extended Antoine vapor pressure equations. The condensed phases can be either liquid or crystal. Thus, these constants provide evaluated vapor pressures which professional thermodynamicists believe represent the data within experimental error. 

Most of the thermodynamic data needed to calculate the enthalpy changes shown in Fig. 17.2 can be found in standard tables of thermodynamic data,... 

Parameters a and A for water and n-tetradecane were determined by using tables of thermodynamic data [11. 10] for HP they were calculated by using nonlinear regression and eight points on a four-parameter P(7 )-curve approximation [11] ... 

This paper reviews the literature from 1958 to 1967. It contains extensive tables of thermodynamic data obtained for various systems by spectroscopic methods. 

Without referring to the tables of thermodynamic data, predict the signs of AH° and AS° for the reaction NH3(aq) -5= NH3(g). Explain why the odor of NH3(g) that collects above an aqueous solution of ammonia becomes more intense as the temperature is increased. ... 

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