Free energy change in reaction

Free-energy change in reaction, kcal/g-mol Th reduced with 4 mol Na + 121.96 +58.14 -85.49... 

The free energy change in reaction 34 is much higher Lipmann has calculated it to be about 16,000 cal. In this reaction, not only is water split out, but a C—C bond of a /3-keto acid is formed. 

Having calculated the standai d values AyW and S" foi the participants in a chemical reaction, the obvious next step is to calculate the standard Gibbs free energy change of reaction A G and the equilibrium constant from... 

Reduction Potentials—An Accounting Device for Free Energy Changes in Redox Reactions... 

For infinitely long chains (polymers), terms (Gcx Gex) + (Gdefi Gdefl) will be close to zero. Consequently, in infinitely long chains and polymers, free energy change in the process can be close to the one in similar reactions of low-molecular compounds (P. Flori principle) [10]. 

Values of AG can be used to calculate free energy changes for reactions. The relationship is entirely analogous to that given for enthalpies in Chapter 8 ... 

A schematic diagram of the free energy changes in an electron exchange reaction, showing the intersection of two parabolas. The lighter curve represents n,c the darker one, eng, ncg. 

There is a very special case for self-exchange reactions in which the left side of the equation is identical to the right side. Accordingly, there is no free energy change in the reaction, and the equilibrium constant ( fn) must be unity (Eq. 9.29). 

The free energy changes in metabolic oxidation reactions serve several purposes. Part of this energy appears as heat flows that maintain body temperature and disperse energy to the surroundings. Another portion of the energy... 

The free energy change in a chemical reaction is expressed in the same way as the enthalpy of the reaction is expressed. For example, the free energy change in the reaction... 

Free energy change for reaction HA = H + A" in kcal/mol. Standard state 1 atm., 298 K. For origin of data other than those in parentheses, see Blades et al.58 Estimated acidity value based on relationship with AG U. 

In our description of the Marcus theory of electron-transfer reactions we have found it helpful to plot the free energy change in the three dimensional picture shown in Fig. 10 (Albery, 1975c, 1980). This picture emphasizes that... 

Our problem now is to determine the functional form of this experimental free energy curve for the intrinsic rate constant ki for electron transfer. In addition to the Marcus eq 4, two other relationships are currently in use to relate the activation free energy to the free energy change in electron transfer reactions (15, JL6). 

Here, Ais the free energy change of Reaction 17.3 (kJ mol 1), R is the gas constant (8.3143 J K-1 mol-1), and 7k is absolute temperature (K). Factor co is the reciprocal of the average stoichiometric number, which can be taken as the number of times the rate determining step in Reaction 17.3 occurs per turnover of the reaction (Jin and Bethke, 2005). 

Fig. 22.7. Thermodynamic driving forces for various anaerobic (top) and aerobic (bottom) microbial metabolisms during mixing of a subsea hydrothermal fluid with seawater, as a function of temperature. Since the driving force is the negative free energy change of reaction, metabolisms with positive drives are favored thermodynamically those with negative drives cannot proceed. The drive for sulfide oxidation is the mirror image of that for hydrogentrophic sulfate reduction, since in the calculation 02(aq) and H2(aq) are in equilibrium.

Fig. 5 Free energy changes in the steam reforming, decomposition, dehydrogenation and dehydration of ethanol. The data for water-gas-shift reaction also is included.

Here AGr° is the Gibbs free energy change in the ideal gas phase reaction system when all the gases are in their respective standard states. The equilibrium constant Kp is given in terms of the partial pressures at equilibrium by... 

Figure 4.3 Free energy changes in redox reactions mediated by microbes, (a) Oxidation of reduced inorganic compounds linked to reduction of O2. (b) Oxidation of organic matter CH2O linked to reduction of various organic and inorganic oxidants. pH = 7 and unit oxidant and reductant activities except (Mn +) = 0.2mM and (Fe +) = ImM...

The thermodynamic criterion for spontaneity (feasibility) of a chemical and electrochemical reaction is that the change in free energy, AG have a negative value. Free-energy change in an oxidation-reduction reaction can be calculated from knowledge of the cell voltage ... 

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