FREE ENERGIES OF SOLUTION AND STANDARD FREE ENERGY OF FORMATION OF AMINO ACIDS IN AQUEOUS SOLUTION AT 25°C

1979 ◽  
Vol 57 (2) ◽  
pp. 240-248 ◽  
Author(s):  
J. Peter Guthrie ◽  
Patricia A. Cullimore

From the heats of hydrolysis of enol ethers, the heats of formation of the enol ethers, and thence the free energies of formation of the enol ethers in aqueous solution can be calculated. For this calculation it was necessary to determine the free energies of transfer from the gas phase to aqueous solution. By methods previously published it was possible to estimate the free energy change for the hypothetical hydrolysis reaction leading from the enol ether to the enol, which in turn made possible calculation of the free energy of formation of the enol. Finally the free energy change for enolization in aqueous solution could be calculated using the known free energy of formation of the corresponding keto tautomer. In this way the following were determined: carbonyl compound, pKenol = −log ([enol]/[keto]): acetaldehyde, 5.3; propionaldehyde, 3.9; isobutyraldehyde, 2.8; acetone, 7.2; 2-butanone, 8.3; 3-pentanone, 7.8; cyclopentanone, 7.2; cyclohexanone, 5.7; acetophenone, 6.7.


2019 ◽  
Vol 36 (1) ◽  
pp. 227-233 ◽  
Author(s):  
Isehaq Al-Nafai ◽  
Hojong Kim ◽  
Kwadwo Osseo-Asare

1969 ◽  
Vol 24 (10) ◽  
pp. 1580-1585 ◽  
Author(s):  
Giovanni B. Barbi

Abstract A non-stationary technique of e.m.f. measurements after polarization of solid galvanic cells, previously applied to the determination of the standard free energy of formation of metal oxides, has been extended to intermetallic phases. The chief condition of applicability of this technique to intermetallic compounds is that the rates of recombination of the cathodic reduction products to yield the stable intermetallic phase be high as compared with that of chemical oxidation at the interface with the solid intermediate electrolyte, due to oxygen impurities in the gas phase. In particular, the solid electrolytic cell:(y values expressing the ε-phase iron-rich boundary compositions according to different authors investigations) was examined.Values of the standard free energy of formation of Fe7-yNb2 from the elements, ranging between-3.77+0.72-10-3 T and -5.66+1.09 · 10-3 T kcal/atom were found.


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