Entropy and Gibbs energy of formation

The second-law processing of the combined studies of the decomposition pressure noted above ([1963YEN/LI], [1972KNA/MUL]) also provides a value of the standard entropy of ThOCl2(cr), for which no other experimental determination is available. The derived value  

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The enthalpy, entropy, and Gibbs energy of formation for the reaction... 

Enthalpies, Entropies, and Gibbs Energies of Formation of Lanthanide (III) Oxides at 298.15... 

The standard entropy and Gibbs energy of formation can now be calculated with selected auxiliary data to be ... 

It is apparent from the preceding section that the thermochemical quantities required for metallurgical substances are the enthalpy, entropy, and Gibbs energy of formation. Since the three functions are inter-related, only two of them need be determined experimentally for any one substance. Since the enthalpy and entropy of formation are not independent of temperature, heat capacities should also be known, although these can often be estimated for condensed phases with some reliability. It may be recalled that the heat capacity enters the relevant calculations in the following form ... 

Consideration of the composition dependence requires the introduction of a further set of thermodynamic quantities. So far it has been assumed that the enthalpies, entropies, and Gibbs energies of formation are the molar quantities for the formation of the compound from the component elements. These are termed the integral quantities. However, for experimental as well as practical reasons, the corresponding partial quantities must be defined. The partial molar quantities, say AZb, are related to the integral quantity by the formula ... 

Holley Jr, C.E., E.J. Huber Jr and F.B. Baker, 1968, The Enthalpies, Entropies and Gibbs energies of Formation of the Rare Earth Oxides, in Progress in the Science and Technology of the Rare Earths, Vol. 3, ed. L. Eyring (Pergamon Press, Oxford) p. 343. 

ENTHALPIES AND GIBBS ENERGIES OF FORMATION, ENTROPIES, AND HEAT CAPACITIES... 

The tables in this section contain values of the enthalpy and Gibbs energy of formation, entropy, and heat capacity at 298.15 K (25°C). No values are given in these tables for metal alloys or other solid solutions, for fused salts, or for substances of undefined chemical composition. 

TABLE 6.1 Enthalpies and Gibbs Energies of Formation, Entropies, and Heat Capacities of Organic Compounds... 

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