Gibbs free energy table

Equation (1.12), the expression of the equilibrium state of a reaction, is known as the mass action law and is a direct consequence of the minimization of Gibbs free energy. Table 1.1 presents equilibrium constants and standard free energy changes for some common environmental... 

As noted above, it is very difficult to calculate entropic quantities with any reasonable accmacy within a finite simulation time. It is, however, possible to calculate differences in such quantities. Of special importance is the Gibbs free energy, as it is the natoal thermodynamical quantity under normal experimental conditions (constant temperature and pressme. Table 16.1), but we will illustrate the principle with the Helmholtz free energy instead. As indicated in eq. (16.1) the fundamental problem is the same. There are two commonly used methods for calculating differences in free energy Thermodynamic Perturbation and Thermodynamic Integration. 

Table 9 shows that the value of AGn of the cooperative interaction between bonding centers is within the error in the determination of integral AG values. This fact can either indicate the slight mutual influence of the centers or be caused by the compensation between the enthalpy and entropy components of Gibbs free energy. 

Table 4.3 summarizes values taken from the JANAF tables for the Gibbs free energy functions and standard enthalpies of formation for a few common substances. The JANAF tables provide a more complete tabulation. 

Example 4.1 Use the Gibbs free energy functions from Table 4.3 to calculate ArG° at 1000 K for the reaction... 

Table 9.1 Standard heat capacities, entropies, enthalpies of formation, and Gibbs free energies of formation at T = 298.15 K. ...

Table A4.6 gives the internal rotation contributions to the heat capacity, enthalpy and Gibbs free energy as a function of the rotational barrier V. It is convenient to tabulate the contributions in terms of VjRTagainst 1/rf, where f is the partition function for free rotation [see equation (10.141)]. For details of the calculation, see Section 10.7c.

TABLE 7.6 Examples of the TABLE 7.7 Standard Gibbs Free Energies of Formation at 25°C (kJ-mol Ij ... 

Standard Gibbs free energies of formation can be determined in various ways. One straightforward way is to combine standard enthalpy and entropy data from tables such as Tables 6.5 and 7.3. A list of values for several common substances is given in Table 7.7, and a more extensive one appears in Appendix 2A. 

STRATEGY We write the chemical equation for the formation of HI(g) and calculate the standard Gibbs free energy of reaction from AG° = AH° — TAS°. It is best to write the equation with a stoichiometric coefficient of 1 for the compound of interest, because then AG° = AGf°. The standard enthalpy of formation is found in Appendix 2A. The standard reaction entropy is found as shown in Example 7.9, by using the data from Table 7.3 or Appendix 2A. 

We are free to choose either K or Kc to report the equilibrium constant of a reaction. However, it is important to remember that calculations of an equilibrium constant from thermodynamic tables of data (standard Gibbs free energies of formation, for instance) and Eq. 8 give K, not Kc. In some cases, we need to know Kc after we have calculated K from thermodynamic data, and so we need to be able to convert between these two constants. 

Self-Test 12.3B The reaction taking place in the silver cell used in some cameras and wristwatches is Ag20(s) + Zn(s) - 2 Ag(s) + ZnO(s), and the emf of the cell when new is 1.6 V. What is the reaction Gibbs free energy (See Table 12.2.)... 

The changes in free energy of formation of Reaction (1) are shown in Fig. 2.1 as a function of temperature. " The values of AG were calculated using Eq. (1) above for each temperature. The Gibbs free-energy values of the reactants and products were obtained from the JANAF Tables.1 Other sources of thermodynamic data are listed inRef 6. These sources are generally accurate and satisfactory forthe thermodynamic calculations of most CVD reactions they are often revised and expanded. 

TABLE 7.2 Standard Enthalpies and Gibbs Free Energies of Formation (Values are joules per mole of the substance formed)... 

A table of input parameters for the above thermodynamic data used in the computations was provided. The enthalpy and Gibbs free energy changes are summarized in Schemes 62 and 63 below, respectively. 

Using ln40=3.689 and MT = 18.292kJmoP1, and thermochemical Gibbs free energy at 2200 K from Barin and Knacke (1973), we make Table 6.4. We recognize in the four columns below the components C, O, N and H, the 6x4 component matrix B. 

Table 6.6. The component matrix and Gibbs free energy of formation for various minerals in the...

Table 2 illustrates the effect of the Gibbs free energy on the spontaneity of a chemical/biochemical reaction and the resulting release of energy. Thus, it is useful to use AG values for any biochemical reaction mediated by microbes to determine whether energy is liberated for work, and how much energy is liberated. 

Table 2. The effect of the Gibbs free energy on the spontaneity of a chemical reaction ...

The Gibbs free energy reaction profiles in Fig. 16 have been calculated from the results in Table 16 and the mechanism in (30) and refer to reaction in a 1 1 2-methylphenol buffer at buffer concentrations of 0.001 and 0.1 moldm" (Fig. 16(a) and (b), respectively). TS(1) is the transition state for opening of the intramolecular hydrogen bond and TS(2) is the transition... 

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