Gibb’s free energy change

On the basis of the thermodynamic expression, the Gibb s free-energy change for mixing in solution can in turn be related to the activity of a solute at equilibrium as described by Equations 3.7 through 3.10 in Chapter 2 of this book, namely,... 

If H2 is produced inside the cell, AE0 is negative the Gibbs s free energy change, AG0 =-nFAE0 , becomes positive, 23.9 kJ/mol at pH 8 (well known inside pH of Escherichia coli), and the equilibrium constant, K =[NAD+] [H2]/[NADH], becomes 6.5xl0 5. This means that if H2 is produced inside the cell, only 10 " atm of partial H2 pressure will stop H2 production. But, if H2 is produced outside the cell at pH 6 and NADH is oxidized inside the cell at pH 8, AFV becomes nearly 0 and therefore H2 production is possible even at approx. 1 atm of partial pressure of H2. In fact, bacteria produced H2 continuously under a partial pressure 0.6 atm. 

TABLE 11.14 Thermodynamic Properties for Stepwise Enthalpy, Entropy, and Gibb s Free Energy Changes for the Hydration of 02( ) [23]... 

Thermodynamic reaction equilibrium for the naphthalene and tetralin hydrogenation to decalins was calculated according to Gibb s free energy change by the FLOWBAT program [12]. The results predict full conversion of both n hthalene and tetralin to decalins under the conditions studied. Moreover, thermodynamics favours the formation of trans-decalin, 93.5-96.6% in the temperature range 85-160°C [12]. The thermodynamic equilibrium of and A -octalin was not calculated since the required thermodynamic properties were not available. Weitkamp [7] has reported that the equilibrium ratio of the octalins varies from 15 to 3.5 at 0-200 C (5.9 and 3.6 at 100 and 177°C, respectively), with A -octalin the major component. 

Cell potentials are related to values of Gibb s free energy changes, AG (Chapter 15).)... 

The maximum amount of electrical work that can be done by an electrochemical cell is equal to the Gibb s free energy change (Chapter 15), AG (provided the temperature and pressure remain constant). The equation below gives the exact relationship between the Gibb s free energy and the cell potential ... 

AG Gibb s free energy change in the redox reaction... 

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