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  • entropy change  (3)
  • heat capacity changes  (3)
  • 1995-1999  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Enthalpies of Dilution of Aqueous Solutions of NaOH, KOH, and CsOH at 300, 325, and 350°C (1998)
    Springer
    Journal of solution chemistry 27 (1998), S. 183-194 
    Details
    ISSN: 1572-8927
    Keywords: Dilution enthalpies ; activity coefficients ; alkali metal hydroxides ; equilibrium constants ; enthalpy changes ; entropy changes ; heat capacity changes ; high temperature ; aqueous solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Dilution enthalpies, measured using isothermal flow calorimetry, are reported for aqueous solutions of KOH and CsOH at 300°C and 11.0 MPa, 325°C and 14.8 MPa, and for aqueous solutions of NaOH, KOH, and CsOH at 350°C and 17.6 MPa. Previously collected dilution enthalpies for aqueous solutions of NaOH at 300°C and 9.3 MPa and at 325°C and 12.4 MPa were included when fitting the Pitzer parameters. The concentration range of the hydroxide solutions was 0.5–0.02 molal. Parameters for the Pitzer excess Gibbs ion-interaction equation were determined from the fits of the experimental heat data. Equilibrium constants, enthalpy changes, entropy changes, and heat capacity changes for alkali metal ion association with hydroxide ion were estimated from the heat data. For all systems, the enthalpy changes and entropy changes were positive and had accelerating increases with temperature. The resulting equilibrium constants show significant, but smaller, increases with temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022661424398
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  • 2
    Electronic Resource
    Electronic Resource
    Thermodynamics of protonation of AMP, ADP, and ATP from 50 to 125°C (1995)
    Springer
    Journal of solution chemistry 24 (1995), S. 171-200 
    Details
    ISSN: 1572-8927
    Keywords: Equilibrium constant ; protonation of AMP ; ADP, ATP ; enthalpy change ; entropy change ; heat capacity change ; flow calorimetry ; elevated temperatures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The interaction of adenosine 5′-monophosphate (AMP), adenosine 5′-diphosphate (ADP), and adenosine 5′-triphosphate (ATP) ions with protons in aqueous solution has been studied calorimetrically from 50 to 125°C and 1.52 MPa. At each temperature, the reaction of acidic AMP with tetramethylammonium hydroxide was combined with the heat of ionization for water to obtain the enthalpy of protonation of AMP, while the reactions of HCl with deprotonated tetramethylammonium salts of ADP and ATP were used to obtain the enthalpies of protonation of ADP and ATP. Equilibrium constant K, enthalpy change ΔHo, entropy change ΔSo, and heat capacity change ΔC p o values were calculated for the stepwise protonation reactions as a function of temperature. The reactions involving the first protonation of AMP, ADP, and ATP and the third protonation of ADP and ATP were endothermic over the temperature range studied, while that involving the second protonation is exothermic for AMP and ADP, but is exothermic below 100°C and endothermic at 125°C in the case of ATP. Consequently, log K values for the first and third protonation reactions (phosphate groups) increase while those for the second protonation reaction (N1-adenine) decrease in the cases of AMP and ADP and go through a minimum in the case of ATP as temperature increases. The ΔHo values for all protonation reactions increase with temperature. The magnitude and the trend for the ΔHo, ΔSo, and ΔC p o values with temperature are discussed in terms of solvent-solute interactions. The magnitude of the ΔC p o values for the second protonation is consistent with little interaction between the phosphate ion and the protonated N1 site of the adenine moiety in AMP, but indicates moderate interaction between these groups in ADP, and strong interaction in ATP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00972840
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  • 3
    Electronic Resource
    Electronic Resource
    Enthalpies of Dilution of Aqueous Solutions of LiCl, KCl, and CsCl at 300, 325, and 350°C (1997)
    Springer
    Journal of solution chemistry 26 (1997), S. 47-61 
    Details
    ISSN: 1572-8927
    Keywords: Dilution enthalpies ; activity coefficient ; alkali metal chlorides ; equilibrium constants ; enthalpy changes ; entropy changes ; heat capacity changes ; high temperature ; aqueous solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Dilution enthalpies, measured using isothermal flow calorimetry, are reported for aqueous solutions of LiCl, KCl, and CsCl at 300°C and 11.0 MPa, 325°C and 14.8 MPa, and 350°C and 17.6 MPa. The concentration range of the chloride solutions was 0.5 to 0.02 m. Parameters for the Pitzer excess Gibbs ion-interaction equation were determined from the fits of the experimental heat data. Equilibrium constants, enthalpy changes, entropy changes, and heat capacity changes for ion association of the chloride salts were estimated from the heat data. For all systems, the enthalpy and entropy changes were positive and had accelerating increases with temperature. The resulting equilibrium constants show significant, but smaller, increases with temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1024485028264
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  • 4
    Electronic Resource
    Electronic Resource
    Enthalpies of dilution of aqueous solution of LiCl, KCl, and CsCl at 300, 325, and 350°C (1997)
    Springer
    Journal of solution chemistry 26 (1997), S. 47-61 
    Details
    ISSN: 1572-8927
    Keywords: Dilution enthalpies ; activity coefficient ; alkali metal chlorides ; equilibrium constants ; enthalpy changes ; entropy changes ; heat capacity changes ; high temperature ; aqueous solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Dilution enthalpies, measured using isothermal flow calorimetry, are reported for aqueous solutions of LiCl, KCl, and CsCl at 300°C and 11.0 MPa, 325°C and 14.8 MPa, and 350°C and 17.6 MPa. The concentration range of the chloride solutions was 0.5 to 0.02m. Parameters for the Pitzer excess Gibbs ion-interaction equation were determined from the fits of the experimental heat data. Equilibrium constants, enthalpy changes, entropy changes, and heat capacity changes for ion association of the chloride salts were estimated from the heat data. For all systems, the enthalpy and entropy changes were positive and had accelerating increases with temperature. The resulting equilibrium constants show significant, but smaller, increases with temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02439443
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  • 5
    Electronic Resource
    Electronic Resource
    New 2-methylenepropylene-bridged cryptands with high sodium ion selectivity: A thermodynamic study of complexation (1995)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 23 (1995), S. 223-231 
    Details
    ISSN: 1573-1111
    Keywords: Cryptand ; alkali metal ion selectivities ; equilibrium constant ; enthalpy change ; entropy change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermodynamic quantities for the interactions of mono- and tri(2-methylenepropylene)-bridged cryptands, cryptand [3.3.1], cryptand [2.2.2], and 18-crown-6-with Na+, K+, Rb+, and Cs+ have been determined by calorimetric titration in an 80:20 (v/v) methanol: water solution at 25°C. Incorporation of the 2-methylenepropylene (−CH2C(=CH2)CH2−) bridge(s) into cryptand [2.2.2] results in a large change in the ligand-cation binding properties. Tri(2-methylenepropylene)-bridged cryptand [2.2.2] (2) shows high selectivity factors for Na+ over K+ and other alkali cations, while 2-methylenepropylene-bridged cryptand [2.2.2.] (1) selects K+ over Na+, as does cryptand [2.2.2]. The K+/Na+ selectivity is reversed with increasing number of 2-methylenepropylene bridges. This observation indicates that increasing the number of 2-methylenepropylene bridges on cryptand [2.2.2] favors complexation of a small cation over a large one. The logK values for the formation of 1 and 2 complexes (except 1-Cs+ and 2-Na+) decrease as compared with those for the corresponding [2.2.2] complexes. Formation of six-membered chelate ring(s) by the propyleneoxy unit(s) of 1 and 2 with a cation stabilizes the cryptate complexes of the small Na+ and destabilizes the complexes of large alkali metal cations. Thermodynamic data indicate that the stabilities of the cryptate complexes studied are dominated mostly by the enthalpy change. In most cases, both stabilization of Na+ complexes and destabilization of the complexes of large alkali metal cations by six-membered chelate ring(s) also result from an enthalpic effect. Cryptand [3.3.1] shows a selectivity for K+ over Cs+, despite its two long CH2(CH2OCH2)3CH2 bridges. The [3.1] macroring portion of [3.3.1]may be too small to effectively bind the Cs+, resulting in the low stability of the Cs+ complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00709580
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  • 6
    Electronic Resource
    Electronic Resource
    Complexation of Metal Ions with Azacrown Ethers Bearing an 8-Hydroxyquinoline Side Arm (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 29 (1997), S. 259-268 
    Details
    ISSN: 1573-1111
    Keywords: Crown ether ; metal ion selectivity ; equilibrium constant ; enthalpy change ; entropy change ; 8-hydroxyquinoline side arm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermodynamic quantities (log, K, ΔH, and TΔS) for theinteractions of six azacrown ethers each bearing an 8-hydroxyquinoline (CHQ)side arm (1-6) with Na+, K+, Ba2+, and Cu2+ were determined by calorimetrictitration in methanol solution at 25°C. The results indicate that theseligands form stable complexes with the cations studied. Ligands 1 and 3 thathave CHQ attached through position 7 (next to the OH group) show highselectivity for Cu2+ (log K values of 8.12 and 9.44, respectively) over Na+,K+, and Ba2+ by more than four orders of magnitude. On the other hand,ligands 2 and 4 that have CHQ attached through position 2 (next to thequinoline nitrogen group) form more stable complexes with Na+, K+, and Ba2+,but less stable complexes with Cu2+, than ligands 1 and 3. All ligandsinteract more strongly with K+ than with Na+. The K+/Na+ selectivity forligands 4 and 5 is about 1.5 log K units. All complexation reactions displaynegative enthalpy changes. In most cases the entropy changes are alsonegative, indicating that formation of the complexes is enthalpy driven. 1HNMR spectral experiments demonstrate coordination of the cations by alldonor atoms of the ligands including those of the CHQ arm. In all cases, theOH signal is observed in the 1H NMR spectra, suggesting that thecomplexation with the cations does not involve deprotonation of the CHQgroups in the ligands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007959629553
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