scholarly journals THE VAPOR PRESSURES AND FREE ENERGIES OF THE HYDROGEN HALIDES IN AQUEOUS SOLUTION; THE FREE ENERGY OF FORMATION OF HYDROGEN CHLORIDE.

1919 ◽  
Vol 41 (12) ◽  
pp. 1991-2001 ◽  
Author(s):  
Stuart J. Bates ◽  
H. Darwin Kirschman
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Hydrogen Chloride ◽  
Vapor Pressures ◽  
Free Energies ◽  
Hydrogen Halides ◽  
Free Energy Of Formation ◽  
Energy Of Formation

The enol content of simple carbonyl compounds: a thermochemical approach

1979 ◽  
Vol 57 (2) ◽  
pp. 240-248 ◽  
Author(s):  
J. Peter Guthrie ◽  
Patricia A. Cullimore
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Carbonyl Compounds ◽  
Free Energy Change ◽  
Energy Change ◽  
Free Energies ◽  
Enol Ethers ◽  
Free Energy Of Formation ◽  
Hydrolysis Of ◽  
Energy Of Formation

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.

Energetics of acetic acid enol in aqueous solution. A new method for thermodynamic estimation

1993 ◽  
Vol 71 (12) ◽  
pp. 2123-2128 ◽  
Author(s):  
J. Peter Guthrie
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Acetic Acid ◽  
Satisfactory Agreement ◽  
Marcus Theory ◽  
New Method ◽  
Free Energy Of Formation ◽  
Independent Estimate ◽  
Energy Of Formation

A new disproportionation calculation allows the estimation of the free energy of formation of the enol of acetic acid as 65 ± 2 kcal/mol. The value of pKE derived from this free energy, pKE = 21 ± 2, is in satisfactory agreement with information from the literature about rates of exchange. Analysis of the data on rates of exchange of the C-H protons of acetic acid using Marcus theory allows an independent estimate of the enol content. Exchange in acid and in base lead to internally consistent estimates, pKE = 19.3 ± 2.2, which are within the combined uncertainties of the values from the thermodynamic estimate.

Tautomeric equilibria and pKa values for 'sulfurous acid' in aqueous solution: a thermodynamic analysis

1979 ◽  
Vol 57 (4) ◽  
pp. 454-457 ◽  
Author(s):  
J. Peter Guthrie
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Aqueous Solutions ◽  
Equilibrium Constants ◽  
Acid Solutions ◽  
Sulfurous Acid ◽  
Free Energy Of Formation ◽  
Dilute Aqueous Solutions ◽  
Sulfite Ion ◽  
Energy Of Formation

The free energy of formation of dimethyl sulfite in aqueous solution can be calculated as −91.45 ± 0.79 kcal/mol; this calculation required measurement of the solubility of dimethyl sulfite. From this value and the pKa of SO(OH)2, using previously reported methods, the free energy of formation of SO(OH)2 can be calculated to be −129.26 ± 0.89 kcal/mol. Comparison of this value with the value obtained from the free energy of formation of 'sulfurous acid' solutions, calculated from the free energy of formation of sulfite ion and the apparent pKa, values, permits evaluation of the free energy of covalent hydration of SO2 as 1.6 + 1.0 kcal/mol, in agreement with earlier qualitative spectroscopic observations. From the apparent pKa and the anticipated pKa values for the tautomers (SO(OH)2, pK1 = 2.3; HSO2(OH), pK1 = −2.6) it is possible to calculate the free energy change for tautomerization of SO(OH)2 to H—SO2(OH) as +4.5 ± 1.2 kcal/mol. All equilibrium constants required for Scheme 1, describing the species present in dilute aqueous solutions of SO2, have been calculated. In agreement with previous Raman studies the major tautomer of 'bisulfite ion' is calculated to be H—SO3−.

The tetrahedral intermediate from the hydration of N-methylformanilide

1993 ◽  
Vol 71 (12) ◽  
pp. 2109-2122 ◽  
Author(s):  
J. Peter Guthrie ◽  
Jonathan Barker ◽  
Patricia A. Cullimore ◽  
Jinqiao Lu ◽  
David C. Pike
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Dimethyl Acetal ◽  
Heat Of Formation ◽  
Basic Solution ◽  
Tetrahedral Intermediate ◽  
Rate Determining Step ◽  
Free Energy Of Formation ◽  
Hydrolysis Of ◽  
Energy Of Formation

Heats of hydrolysis of N-methylformanilide dimethyl acetal have been measured in basic solution. The heat of formation of N-methylformanilide was obtained by determining the equilibrium constant in aqueous solution for its formation from formic acid and N-methylaniline as a function of temperature:[Formula: see text]. These data permit the calculation of the heat of formation of N-methylformanilide dimethyl acetal, [Formula: see text]. The free energy of formation of the tetrahedral intermediate in the hydrolysis of N-methylformanilide was calculated by methods we have previously reported. Consideration of the energetics of the intermediates and the known rates of reaction leads to the conclusion that the rate-determining step for alkaline hydrolysis is cleavage of the C—N bond.

The Free Energies of Hydration of Gaseous Ions

1948 ◽  
Vol 1 (4) ◽  
pp. 480 ◽  
Author(s):  
NS Hush
Keyword(s):  
Free Energy ◽  
Water Molecule ◽  
Pure Water ◽  
Free Energies ◽  
The Real ◽  
Free Energy Of Formation ◽  
Energy Of Hydration ◽  
Free Energy Of Hydration ◽  
Molecule Interaction ◽  
Energy Of Formation

Values of hydration energies of individual ions have usually been obtained by division of sums of energies of hydration of pairs of ions, and those calculated by different authors are usually mutually inconsistent. " Experimental " figures, whenever these are quoted, have always been obtained by assuming the truth of theoretical equations whose accuracy has not been independently checked. The distinction between free energy of ion/water-molecule interaction and the real free energy of hydration of a gaseous ion is pointed out, and the importance of Klein and Lange's measurement of the Volta-potential Hg/Hg+ (soln.), which makes possible the direct calculation of real free energies of hydration of individual ions, thus providing a check on theoretical values, is emphasized. Utilizing this value, the equation - ΔFh� = - ΔFf� + ΔFi� + ΔFs�- 103.92 z kcal. (where ΔFs� is the free energy of formation of the gaseous monatomic element, ΔFi� is the free energy of ionization, ΔFf�is the free energy of formation of the aqueous ion, and ΔFh� is the real free energy of hydration of the ion, of valency z, at 298.2� K.) is derived from fundamental considerations. By means of this equation, the real free energies of hydration of 49 ions are calculated, using the most reliable data. It is proposed that these be provisionally accepted as standard values. Several subsidiary values for important ions are calculated indirectly. The difference between ΔFh� and the free energy of ion/water-molecule interaction is discussed in relation to the surface structure of water : a value of -0.30 v. is derived for the X-potential at the surface of pure water, and it is concluded that at the water/gas interface the positive poles of the surface layer are oriented towards the gas phase. The applicability of a modified Born equation in the calculation of free energies of hydration is discussed, and a modified equation is proposed which yields values of ΔFh� for gaseous ions with noble gas structure in excellent agreement with those calculated independently by the method described above.

Thermodynamics of methanesulfonic acid, methanesulfonyl chloride, and methyl methanesulfonate

1998 ◽  
Vol 76 (6) ◽  
pp. 929-936 ◽  
Author(s):  
J Peter Guthrie ◽  
Allan R Stein ◽  
Anthony P Huntington
Keyword(s):  
Aqueous Solution ◽  
Methanesulfonic Acid ◽  
Heat Of Formation ◽  
Methyl Methanesulfonate ◽  
Molecular Orbital Calculations ◽  
Heat Of Reaction ◽  
Free Energies ◽  
Methanesulfonyl Chloride ◽  
Free Energy Of Formation ◽  
Energy Of Formation

The heat of formation of liquid methanesulfonic acid, -178.09 ± 1.48, was determined by measuring the heat of reaction of methyl thiolacetate with aqueous hypochlorite solution to give aqueous methanesulfonate and acetate. The heats of formation of liquid methanesulfonyl chloride, -126.91 ± 1.54, and methyl methanesulfonate, -164.34 ± 1.58, were determined by measuring the heats of reaction of methanesulfonyl chloride with water or methanol in the presence of a suitable basic catalyst. Heats of vaporization (based on vapor-pressure data), entropies (based on ab initio molecular orbital calculations), and free energies of transfer from gas phase to aqueous solution were calculated leading to values for the free energies of formation in aqueous solution. The free energies of formation so determined were methanesulfonic acid, -151.72 ± 2.68, methanesulfonyl chloride, -101.29 ± 1.96, and methyl methanesulfonate, -127.28 ± 2.08. From these values the free energies of hydrolysis (leading to unionized methanesulfonic acid) are methanesulfonyl chloride, -25.11 ± 3.04, and methyl methanesulfonate, -9.90 ± 2.48.Key words: sulfonic acids, heat of formation, free energy of formation, hydrolysis.

scholarly journals Estimating Free Energies of Formation of Titanate () and Zirconate () Pyrochlore Phases of Trivalent Lanthanides and Actinides

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Anpalaki J. Ragavan ◽  
Dean V. Adams
Keyword(s):  
Free Energy ◽  
First Principles ◽  
Linear Free Energy Relationship ◽  
Free Energies ◽  
Empirical Parameter ◽  
Trivalent Lanthanides ◽  
Linear Free Energy ◽  
Free Energy Of Formation ◽  
The Difference ◽  
Energy Of Formation

A linear free energy relationship was developed to predict the Gibbs free energies of formation (, in kJ/mol) of crystalline titanate (M2Ti2O7) and zirconate (M2Zr2O2) pyrochlore families of trivalent lanthanides and actinides (M3+) from the Shannon-Prewitt radius of M3+ in a given coordination state (, in nm) and the nonsolvation contribution to the Gibbs free energy of formation of the aqueous M3+ (). The linear free energy relationship for M2Ti2O7 is expressed as . The linear free energy relationship for M2Zr2O7 is expressed as . Estimated free energies were within 0.73 percent of those calculated from the first principles for M2Ti2O7 and within 0.50 percent for M2Zr2O7. Entropies of formation were estimated from constituent oxides (J/mol), based on an empirical parameter defined as the difference between the measured entropies of formation of the oxides and the measured entropies of formation of the aqueous cation.

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