Heat Capacities and Transformations

It is necessary to specify zero ionic strength here because Debye-HUckel adjustments for ionic strength depend on the temperature. Heat capacities and transformed heat capacities are discussed in an Appendix to this chapter. However, since there is not very much information in the literature on heat capacities of species or transformed heat capacities of reactants, the treatments described here are based on the assumption that heat capacities of species are equal to zero. When molar heat capacities of species can be taken as zero, both standard enthalpies of formation and standard entropies of formation of species are independent of temperature. When Af H° and Af 5° are independent of temperature, standard Gibbs energies of formation of species at zero ionic strength can be calculated using... 

There is some literature data on heat capacities and transformed heat capacities, but not enough to justify including them in the general treatments here, but they are of interest and may not be negligible. The adjustment of the heat capacity of a species for the ionic strength depends on both the first and second derivatives of the coefficient alpha in the Debye-Huckel equation. 

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