Gibbs free energy for

Example. Calculate the change in Gibbs free energy for the reaction of methanol and oxygen to produce formaldehyde and water at reaction temperatures of 600, 700, 800, 900, and 1,000°K ... 

A copy (5V4 inch floppy disk) of a menu-driven computer program to calculate Gibbs free energy of formation and change in Gibbs free energy for reactions (including random access data file of compound coefficients) is available for a nominal fee. For details, contact C. L. Yaws, Dept, of Chem. Eng. Lamar University, P.O. Box 10053, Beaumont, Texas 77710, USA. 

Vibrational Contribution to the Gibbs Free Energy For a Linear Diatomic Molecule From equations (10.84) and (10.101)... 

The change in Gibbs free energy for a process is a measure of the change in the total entropy of a system and its surroundings at constant temperature and pressure. Spontaneous processes at constant temperature and pressure are accompanied by a decrease in Gibbs free energy. 

Calculate the standard reaction entropy, enthalpy, and Gibbs free energy for each of the following reactions from data found in Appendix 2A ... 

Heavy water is deuterium oxide, D20. The standard reaction Gibbs free energy for the autoprotolysis of pure deuterium oxide is +84.8 kj-mol 1 at 298 K. (a) If pD is defined analogously to pH, what is the pD of pure D20 at 298 K ... 

Predict the standard cell emf and calculate the standard reaction Gibbs free energy for galvanic cells having the following cell reactions ... 

The Gibbs free energy for the reaction is related to the equilibrium cell potential ( 0) (Equation 6.4). For the reaction between hydrogen and oxygen to produce water, n, the number of electrons per molecule participating in the electrochemical reaction is 2 and AG has a value of —37.2 kJ mol giving Eq a value of 1.23 V... 

Here, AS° = AS i + AS n, but since identical vibrational levels have been assumed for the two electronic levels, AS jb = 0. In addition, AS j is related to the electronic degeneracies of the two levels by ASei = K In ( l/ h)- Finally, if the transformation takes place at constant pressure, AH° = NAE where AE is defined as above. Consideration of the Gibbs free energy for an assembly of N molecules thus produces the same relation for the HS fraction Uh as the potential energy for the isolated molecule, if only the interaction between the molecules is neglected. 

The Gibbs free energy for the transition from ES to ES" is related to the value of kC3, as described by Equation (2.3) ... 

The 1.8 kcal mol 1 less favorable change in Gibbs free energy for the addition of water to [18+] to give [18]-OH in 50/50 (v/v) trifluoroethanol/water (p/CR = -11.3)104 than for addition of water to Me-[6+] in the same solvent (pATR = -12.6)13 shows that the former carbocation is stabilized relative to the alcohol. This stabilization may be the result of the smaller entropic price paid to restrict the / —CH bonds in the five-membered ring at [18+] to conformations that are favorable for hyperconjugation with the cationic carbon. 

Brinkley (1947) published the first algorithm to solve numerically for the equilibrium state of a multicomponent system. His method, intended for a desk calculator, was soon applied on digital computers. The method was based on evaluating equations for equilibrium constants, which, of course, are the mathematical expression of the minimum point in Gibbs free energy for a reaction. 

The change in the Gibbs free energy for this reaction, AGr, can be related to the partial pressure of the oxygen gas, po2, using the equation ... 

Semianalytical mean-field theories of block copolymer micellization were formulated by Noolandi et al. [ 197] and by Leibler et al. [198]. In the approach of Noolandi et al., the micellar characteristics were obtained through a minimization of the Gibbs free energy for an isolated micelle. This was applied to PS-PB micelles, and the obtained theoretical values were in good agreement with the experimental ones. 

The Gibbs free energy for the following process is 25.2 kJ/mol. Determine the equilibrium constant for this process at 25°C ... 

The Gibbs free energy for a spontaneous process has a sign. 

Molecules in the surface or interfacial region are subject to attractive forces from adjacent molecules, which result in an attraction into the bulk phase. The attraction tends to reduce the number of molecules in the surface region (increase in inter-molecular distance). Hence work must be done to bring molecules from the interior to the interface. The minimum work required to create a differential increment in surface dA is ydA, where A is the interfacial area and y is the surface tension or interfacial tension. One also refers to y as the interfacial Gibbs free energy for the condition of constant temperature, T, pression, P, and composition (n = number of moles)... 

The Gibbs free energy is the best single thermodynamic indicator of whether a reaction will be spontaneous (review the Thermodynamics chapter). The Gibbs free energy for a reaction can be calculated from the E° of the reaction using the following equation ... 

The standard cell potetial can be used to calculate the Gibbs free energy for the reaction AG° = -nFE tXV Know how to use this equation. 

Williams calculated molar Gibbs free energies for the reactants, the encounter complexes and the transition states for both the uncatalysed and enzyme-catalysed reactions using ab initio methods at the 4-31G level of SCF-MO theory. The secondary a-deuterium (kCHJkcoJ, the I2C/13C and 12C/14C KIEs were also calculated for these reactions using equation (5). 

AG° is the standard Gibbs free energy for the reaction at 298°K R is the ideal gas constant and T is 298°K. Since the actual temperature of most slurries or solutions in flue gas scrubbing applications usually does not exceed 50°C, the value of the equilibrium constant can be determined at some temperature other than 298°K by using the van t Hoff equation... 

Gibbs free energies of water sorption, AG "(/l), can be extracted from isopiestic vapor sorption isotherms this analysis shows that AG (T) < AG", where AG" = -44.7 kj moH is the Gibbs free energy for vapor sorption at a free water surface at ambient condihons. Water absorbed by the membrane is therefore more strongly bound than water at a free bulk water surface this affirms the hydrophilic nature of water sorption in PEMs. 

---