Enthalpy solution limiting table

TABLE 8.6 Limiting Enthalpies of Solution, at 25°C, in Kilojoules per Mole ... 

Calorimetric measurements yield enthalpy changes directly, and they also yield information on heat capacities, as indicated by equation 10.4-1. Heat capacity calorimeters can be used to determine Cj , directly. It is almost impossible to determine ArCp° from measurements of apparent equilibrium constants of biochemical reactions because the second derivative of In K is required. Data on heat capacities of species in dilute aqueous solutions is quite limited, although the NBS Tables give this information for most of their entries. Goldberg and Tewari (1989) have summarized some of the literature on molar heat capacities of species of biochemical interest in their survey on carbohydrates and their monophosphates. Table 10.1 give some standard molar heat capacities at 298.15 K and their uncertainties. The changes in heat capacities in some chemical reactions are given in Table 10.2. 

Klushina, Selivanova, and Poltavtseva prepared crystalline Li2Se03 H20 and measured the enthalpy of the reaction of the salt with a lead nitrate solution in an electrically calibrated calorimeter. Crystalline lead selenite is formed. In the evaluation of the calorimetric measurements the authors divided the heat evolved by the number of moles of Li2Se03 H20 taken. This is incorrect as the amount of Pb(N03)2 used limits the amount of lead selenite that can be formed. The data have been recalculated to find the enthalpy change of the reaction Li2Se03-H20(cr) + Pb PbSe03(cr) + 2Li + H20(l) in Table A-54. 

The upper limit for the enthalpy of activation is somewhat harder to set. An attempt can be made by noting that the partial molal entropy of e m is estimated to be positive. It is unprecedented for solution of a charged species to cause an increase in entropy of the surrounding medium, and the effect, if real, must be associated with the very dispersed charge of the hydrated electron. If the enthalpy of activation for the reverse of Reaction 1 is greater than the value estimated in Table II, then the partial molal entropy of the hydrated electron in Table I must... 

This very extensive (99 pages) chapter (no. 2 in Volume II) contains a general discussion of the effects of temperature and pressure on activity coefficients for both binary and mixed electrolyte solutions. Properties of interest are the partial molar volume, expansibility, compressibility, heat capacity, and enthalpy. There is also an excellent discussion of methods of estimating partial molar properties in mixed electrolyte solutions. There are 226 references to the literature. Tables of data are presented for Debye-HUckel limiting law slopes for the afJ parent molar volume, enthalpy, heat capacity, expansibility, and compressibility as a function of temperature parameters for the partial molar volumes of 30 aqueous electrolyes at 25 °C parameters for the partial molar expansibility of ten electrolytes at 25 C parameters for the partial molar compressibilities of 33 electrolytes at 25 °C values of the activity coefficients of aqueous NaCl solutions at 25 C as a function of pressure (up to 1000 bars) parameters for the partial molar enthalpies of 59 electrolytes at 25 C parameters for the partial molar heat capacities of 140 electrolytes at 25 °C and tables giving compositions and the partial molar properties of average seawater. 

The properties of ions in solution depend, of course, on the solvent in which they are dissolved. Many properties of ions in water are described in Chapters 2 and 4, including thermodynamic, transport, and some other properties. The thermodynamic properties are mainly for 25°C and include the standard partial molar heat capacities and entropies (Table 2.8) and standard molar volumes, electrostriction volumes, expansibilities, and compressibilities (Table 2.9), the standard molar enthalpies and Gibbs energies of formation (Table 2.8) and of hydration (Table 4.1), the standard molar entropies of hydration (Table 4.1), and the molar surface tension inaements (Table 2.11). The transport properties of aqueous ions include the limiting molar conductivities and diffusion coefficients (Table 2.10) as well as the B-coefficients obtained from viscosities and NMR data (Table 2.10). Some other properties of... 

Fig. 17.7 can be used to estimate enthalpies of solution of other actinide dioxides and to calculate their enthalpies of formation. The relevant data are shown in Table 17.6. A tetravalent P(M) function has also been conceived and plotted [40] but its component terms have large error limits and there are few reliable data points, so that the tetravalent P(M) function is not useful to explain metallic behavior or to predict dioxide thermodynamics. 

Most studies whose primary goal is to characterize the individual polymer molecule and its interaction in an infinitely dilute solution will not be found in this table. However, references to studies of dilute solutions are presented in some of the other tables of Part VII ( Solution Properties ). Most of the reports of changes in free energy on mixing or on dilution cited here have been limited to those that also provide sufficient data to determine the change in the enthalpy (or entropy). References to measurements of solvent activities which can yield information about changes in free energy can be found in Polymer-Solvent Interaction Parameters . 

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