The volumetric and thermochemical properties of aqueous solutions of L-valine, L-leucine, and L-isoleucine at 288.15, 298.15, 313.15, and 328.15 K

1994 ◽  
Vol 72 (6) ◽  
pp. 1489-1494 ◽  
Author(s):  
Michelle M. Duke ◽  
Andrew W. Hakin ◽  
Robert M. McKay ◽  
Kathryn E. Preuss
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aqueous Solutions ◽  
Constant Pressure ◽  
Heat Capacities ◽  
Thermochemical Properties ◽  
Acid System ◽  
Standard State ◽  
Apparent Molar Heat Capacities ◽  
Fitting Procedures

Densities and volumetric heat capacities have been measured for aqueous solutions of L-valine, L-leucine, and L-isoleucine at 288.15, 298.15, 313.15, and 328.15 K. These data have been used to calculate apparent molar volumes, [Formula: see text] and apparent molar heat capacities, [Formula: see text] which in turn have been used to obtain standard state volumes, [Formula: see text] and standard state heat capacities, [Formula: see text] for each aqueous amino acid system. Helgeson, Kirkham, and Flowers equations, for neutral organics in water, have been used to model the calculated standard state volumes and heat capacities of the amino acids as a function of temperature at constant pressure. The results of our fitting procedures may be used to predict the behaviour of [Formula: see text] and [Formula: see text] for the selected amino acid systems outside of the temperature range utilised in this investigation.

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

1994 ◽  
Vol 72 (2) ◽  
pp. 362-368 ◽  
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.

Densities and apparent molar volumes of aqueous aluminum chloride. Analysis of apparent molar volumes and heat capacities of aqueous aluminum salts in terms of the Pitzer and Helgeson theoretical models

1986 ◽  
Vol 64 (2) ◽  
pp. 353-359 ◽  
Author(s):  
Leslie Barta ◽  
Loren G. Hepler
Keyword(s):  
Aqueous Solutions ◽  
Interaction Model ◽  
Partial Molar Volumes ◽  
Theoretical Models ◽  
Heat Capacities ◽  
Apparent Molar Volumes ◽  
Standard State ◽  
Apparent Molar Heat Capacities ◽  
Molar Volumes ◽  
Aqueous Aluminum

Densities of aqueous solutions of AlCl3 (containing dilute HCl) have been measured at 10, 25, 40, and 55 °C with results that have led to defined apparent molar volumes. We have used the Pitzer ion interaction model as the basis for analyzing these apparent molar volumes to obtain standard state (infinite dilution) partial molar volumes of AlCl3(aq) at each temperature. We have also made similar use of apparent molar heat capacities of aqueous solutions of AlCl3–HCl and Al(NO3)3–HNO3 from Hovey and Tremaine to obtain standard state partial molar heat capacities of AlCl3(aq) and Al(NO3)3(aq) at these same temperatures. Finally, the standard state partial molar volumes and heat capacities have been used with the Helgeson–Kirkham semi-theoretical equation of state for aqueous ions to provide a basis for estimating the thermodynamic properties of Al3+(aq) at high temperatures and pressures.

Apparent molar heat capacities and volumes of unsaturated heterocyclic solutes in aqueous solution at 25 °C

1980 ◽  
Vol 58 (7) ◽  
pp. 704-707 ◽  
Author(s):  
Octavian Enea ◽  
Carmel Jolicoeur ◽  
Loren G. Hepler
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Heterocyclic Compounds ◽  
Infinite Dilution ◽  
Heat Capacities ◽  
Group Additivity ◽  
Standard State ◽  
Apparent Molar Heat Capacities ◽  
Partial Molar Heat Capacities

Measurements at 25 °C with flow calorimeters and densimeters have led to heat capacities and densities of aqueous solutions of 15 unsaturated heterocyclic compounds containing nitrogen. From the results of these measurements we have obtained apparent molar heat capacities and volumes of the solutes. Extrapolations to infinite dilution have led to corresponding standard state apparent and partial molar heat capacities and volumes, which have been analyzed in terms of atomic and group additivity relationships.

Apparent molal heat capacities and volumes of amino acids in aqueous polyol solutions

1978 ◽  
Vol 56 (13) ◽  
pp. 1827-1831 ◽  
Author(s):  
Giuseppa DiPaola ◽  
Bernard Belleau
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aqueous Solutions ◽  
Transfer Functions ◽  
Heat Capacities ◽  
Side Chains ◽  
Dilute Solutions ◽  
Flow Microcalorimeter ◽  
Regular Increase ◽  
Apparent Molal Heat Capacities

Densities (24 °C) and volumetric specific beats (25 °C) were measured for amino acids (0.05–0.5 m) containing apolar side chains in water, and in aqueous solutions of glycerol, mannitol, sorbitol, NaCl, urea, and Gu•HCl, with a flow densimeter and flow microcalorimeter respectively.The derived apparent molal quantifies and transfer functions of the amino acids in aqueous polyol solutions reveal no specificities which might explain the origin of the unique behavior of polyols in protein systems. However, the study did reveal a regular increase in the structure-making ability of the amino acid as the hydrophobicity of the side chains increased. This structure-making tendency was reduced significantly in dilute solutions of the higher polyols.

Apparent molar heat capacities and volumes of aqueous solutions of several 1:1 electrolytes at elevated temperatures

1986 ◽  
Vol 64 (5) ◽  
pp. 926-931 ◽  
Author(s):  
Preet P. S. Saluja ◽  
Jacques C. LeBlanc ◽  
Harold B. Hume
Keyword(s):  
Heat Capacity ◽  
Aqueous Solutions ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Constant Pressure ◽  
Solubility Limit ◽  
Heat Capacities ◽  
Apparent Molar Heat Capacities ◽  
Flow Microcalorimeter ◽  
Good Agreement

The results of heat capacity (Cp) and density (d) measurements at 0.6 MPa and in the temperature range 298.15–373.15 K are presented for several 1:1 electrolytes in water. The flow microcalorimeter and densimeter used for these measurements were modificatons of the room-temperature designs. Data were obtained over concentrations ranging from 0.02 to 1.0 mol kg−1 (or to the solubility limit, whichever was lower). The heat capacity of a solution relative to that of water was measured with a precision of ±0.1 mJ K−1 g−1 at all temperatures. The density of a solution relative to that of water was measured with a precision of ±5 μg cm−3. These Cp and d results were used to calculate the apparent molar heat capacities, [Formula: see text], and volumes, [Formula: see text], at 298.15, 323.15, 348.15, and 373.15 K, at a constant pressure of 0.6 MPa. These results are in good agreement with available literature data.

Calorimetric investigations of aqueous amino acid and dipeptide systems from 288. 15 to 328. 15 K

1995 ◽  
Vol 73 (5) ◽  
pp. 725-734 ◽  
Author(s):  
Andrew W. Hakin ◽  
Michelle M. Duke ◽  
Lori L. Groft ◽  
Jocelyn L. Marty ◽  
Matthew L. Rushfeldt
Keyword(s):  
Amino Acid ◽  
Thermodynamic Properties ◽  
Heat Capacities ◽  
Group Additivity ◽  
Standard State ◽  
Apparent Molar Heat Capacities ◽  
Empirical Modelling ◽  
Temperature Dependences ◽  
Calorimetric Investigations ◽  
Capacity Data

Densities and heat capacities have been measured for aqueous solutions of L-asparagine, L-glutamine, glycylglycine, glycyl-L-valine, glycyl-L-asparagine, and glycyl-DL-leucine at 288.15, 298.15, 313.15, and 328.15 K. These data have been used to calculate apparent molar volumes, V2,ø, and apparent molar heat capacities, Cp,2,ø, which in turn have been used to obtain standard state volumes, [Formula: see text] and heat capacities, [Formula: see text] The semi-empirical modelling procedures of Helgeson, Kirkham, and Flowers have been used to subdivide the calculated standard state volume and heat capacity data into solvation and nonsolvation contributions. The nonsolvation components of the standard state properties are used in group additivity analyses. These analyses yield structural contributions to standard state volumes and heat capacities for the CH(NH2)CO2H, CH2, OH, COOH, CH, CONH2, and CONH groups. The temperature dependences of these contributions are discussed. Some comments are reported concerning the practicality of using the thermodynamic properties of aqueous amino acid and peptide systems as the basis for modelling standard state thermodynamic properties of aqueous protein systems. Keywords: heat capacities, densities, volumes, amino acids, peptides, group additivity.

Apparent and partial molar heat capacities and volumes of aqueous HClO4 and HNO3 from 10 to 55 °C

1989 ◽  
Vol 67 (9) ◽  
pp. 1489-1495 ◽  
Author(s):  
Jamey K. Hovey ◽  
Loren G. Hepler
Keyword(s):  
Nitric Acid ◽  
Aqueous Solutions ◽  
Perchloric Acid ◽  
Ionic Species ◽  
Heat Capacities ◽  
Standard State ◽  
Apparent Molar Heat Capacities ◽  
Solvent Interaction ◽  
Partial Molar Heat Capacities ◽  
Temperature Dependences

Apparent molar heat capacities and volumes of aqueous solutions containing HClO4 and HNO3 have been determined from 10 to 55 °C. The temperature dependences of the standard state heat capacities and volumes of ClO4− (aq) and NO3− (aq) from 10 to 55 °C were found to be well represented by the following equations:[Formula: see text]Combination of the experimental results with semiempirical equations for ion–solvent interaction has led to predictions of the standard state volumes and heat capacities for these ionic species at higher temperatures. Keywords: heat capacities, volumes, nitric acid, perchloric acid.

Apparent molar heat capacities and volumes of aqueous electrolytes at 25 °C: Cr(NO3)3, LaCl3, K3Fe(CN)6, and K4Fe(CN)6

1979 ◽  
Vol 57 (21) ◽  
pp. 2798-2803 ◽  
Author(s):  
Jan J. Spitzer ◽  
Inger V. Olofsson ◽  
Prem Paul Singh ◽  
Loren G. Hepler
Keyword(s):  
Aqueous Solutions ◽  
Infinite Dilution ◽  
Heat Capacities ◽  
Aqueous Electrolytes ◽  
Standard State ◽  
Apparent Molar Heat Capacities ◽  
Molar Volumes ◽  
High Charge ◽  
Flow Calorimeter ◽  
Partial Molar Properties

We have used a flow calorimeter and a flow densimeter for measurements at 25 °C of heat capacities and densities of aqueous solutions of four electrolytes of high charge type: LaCl3, Cr(NO3)3, K3Fe(CN)6, and K4Fe(CN)6. Results of these measurements have been used for calculating corresponding apparent molar heat capacities and apparent molar volumes, which have been extrapolated to infinite dilution to obtain the corresponding standard state apparent molar and partial molar properties. Uncertainties resulting from extrapolations of heat capacities are discussed. Results of our measurements are compared with those of earlier related investigations.

Apparent molar heat capacities and volumes of aqueous electrolytes at 25 °C: Na2SO4, K2SO4, Na2S2O3, Na2S2O8, K2S2O8, K2CrO4, Na2MoO4, and Na2WO4

1978 ◽  
Vol 56 (14) ◽  
pp. 1871-1873 ◽  
Author(s):  
Inger V. Olofsson ◽  
Jan J. Spitzer ◽  
Loren G. Hepler
Keyword(s):  
Aqueous Solutions ◽  
Infinite Dilution ◽  
Heat Capacities ◽  
Aqueous Electrolytes ◽  
Standard State ◽  
Apparent Molar Heat Capacities ◽  
Density Measurements ◽  
Dilute Aqueous Solutions

We have made beat capacity and density measurements leading to apparent molar beat capacities and volumes for dilute aqueous solutions of Na2SO4, K2SO4, Na2S2O3, Na2S2O8, K2S2O8, K2CrO4, Na2MoO4, and Na2WO4. We have used these apparent molar quantifies to extrapolate to infinite dilution to obtain the corresponding standard state apparent and partial molar quantities. These latter values have been used in calculation of conventional ionic beat capacities and volumes.

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