TEMPERATURE DEPENDENCE OF APPARENT MOLAR VOLUMES AND VISCOSITY B-COEFFICIENTS OF AMINO ACIDS IN AQUEOUS SODIUM SULFATE SOLUTIONS FROM 15 TO 35°C

Densities, ?, viscosities, ? and refractive indices, n D, of solutions of some amino acids (glycine, DL-alanine, DL-? -amino- n-butyric acid, L-valine and L-leucine) in the concentration range 0.02 to 0.10 m in 5 % (v/v) aqueous glycerol were determined at 298.15, 303.15, 308.15 and 313.15 K. These experimental data were used to calculate the apparent molar volumes, ? v, the infinite dilution apparent molar volumes, ? v 0, the partial molar volumes of transfer, ? v 0 (tr), of the amino acids from aqueous to aqueous glycerol solution, as well as the viscosity A and B coefficients of the Jones-Dole equation of the amino acids. The free energies of activation of viscous flow, ??1 0# and ?? 2 0# per mole of solvent and solute, respectively, were obtained by application of the transition-state theory to the B coefficient data and the corresponding activation enthalpy, ?H*, and entropy, ?S*, were also determined. The ? v 0, B coefficients and ?? 2 0# were found to vary linearly with increasing number of carbon atoms in the alkyl chain of the amino acids, and they were split into contributions from the zwitterionic end groups (NH3 +, COO-) and methylene (CH2) groups of the amino acids. The experimental values of the refractive indices, n D, were used to calculate the molar refractive indices, R D, of the amino acids + aqueous glycerol ternary mixtures. The results were interpreted in the light of the solute-solvent and solute-solute interactions in the mixed solvents.

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The temperature dependence of the mobility of aqueous fluoride ion, and the apparent molar volume of sodium fluoride

Australian Journal of Chemistry ◽

10.1071/ch9771375 ◽

1977 ◽

Vol 30 (6) ◽

pp. 1375 ◽

Cited By ~ 4

Author(s):

T Mallanoo ◽

RH Stokes

Keyword(s):

Temperature Dependence ◽

Molar Volume ◽

Sodium Fluoride ◽

Apparent Molar Volume ◽

Apparent Molar Volumes ◽

Fluoride Ion ◽

Molar Volumes ◽

Aqueous Sodium

Conductances of aqueous sodium fluoride solutions have been measured at 15�, 25� and 45�C to give the limiting mobility of fluoride ion. Apparent molar volumes have been obtained by means of a continuous dilution dilatometer.

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Apparent molar heat capacities and volumes of some aqueous solutions of aliphatic amino acids at 288.15, 298.15, 313.15, and 328.15 K

Canadian Journal of Chemistry ◽

10.1139/v94-056 ◽

1994 ◽

Vol 72 (2) ◽

pp. 362-368 ◽

Cited By ~ 101

Author(s):

Andrew W. Hakin ◽

Michelle M. Duke ◽

Sheri A. Klassen ◽

Robert M. McKay ◽

Kathryn E. Preuss

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Aqueous Solutions ◽

Equilibrium Constants ◽

Heat Capacities ◽

Apparent Molar Volumes ◽

Protein Chemistry ◽

Standard State ◽

Apparent Molar Heat Capacities ◽

Molar Volumes

The thermodynamics of amino acid systems are key to the understanding of protein chemistry. We have found that many previous studies of the apparent molar volumes and heat capacities of aqueous solutions of amino acids were conducted at the standard temperature of 298.15 K. This does not allow for the fact that most biological processes occur at temperatures removed from this standard condition.In an attempt to address this imbalance we have measured densities and heat capacities for aqueous solutions of glycine, L-alanine, L-serine, and L-threonine at 288.15, 298.15, 313.15, and 328.15 K using a Picker flow microcalorimeter. Apparent molar volumes and heat capacities, and the associated standard state partial molar properties have been calculated. Constant pressure variations of revised Helgeson, Kirkham, and Flowers equations have been fitted to calculated standard state volumes and heat capacities over the temperature range 288.15 to 328.15 K. These equations may be used to estimate standard state volumes and heat capacities, and hence equilibrium constants, for aqueous amino acid systems at higher temperatures.

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