scholarly journals Excess partial molar enthalpies of alkane-mono-ols in aqueous solutions

1996 ◽  
Vol 74 (5) ◽  
pp. 713-721 ◽  
Author(s):  
Steven Hiroshi Tanaka ◽  
Hikari Infinity Yoshihara ◽  
Alice Wen-Chi Ho ◽  
Frankie W. Lau ◽  
Peter Westh ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Key Words ◽  
Mole Fraction ◽  
Composition Range ◽  
Hydrophobic Moiety ◽  
Enthalpic Interaction ◽  
Mixing Schemes ◽  
Small Increments ◽  
Partial Molar Enthalpies ◽  
Transition Of Mixing Scheme

Excess partial molar enthalpies, HAE, of methanol, ethanol, and 1- and 2-propanols in aqueous solutions were measured directly, accurately, and in small increments in mole fraction at 25 °C. From these data, the solute–solute enthalpic interactions, HAAE≡N(∂HAE/∂nA), were evaluated for each alcohol. These data indicate that three distinctively different mixing schemes, I, II, and III exist, as was the case for aqueous 2-butoxyethanol previously studied in our laboratory. The transition from mixing scheme I to II appears to take place gradually within a small composition range. As the hydrophobic moiety becomes smaller from 2-butoxyethanol to methanol, the locus of the transition moves to a higher value in mole fraction of the alcohol. At the same time, the range of transition becomes wider and the solute–solute enthalpic interaction weaker. Key words: excess partial molar enthalpies in aqueous solutions, methanol, ethanol, 1-propanol, 2-propanol, enthalpic interaction, transition of mixing scheme.

Excess partial molar entropy of alkane-mono-ols in aqueous solutions at 25°C

2003 ◽  
Vol 81 (2) ◽  
pp. 150-155 ◽  
Author(s):  
Yoshikata Koga ◽  
Peter Westh ◽  
Keiko Nishikawa
Keyword(s):  
Aqueous Solutions ◽  
Key Words ◽  
Preceding Paper ◽  
Aqueous Methanol ◽  
Model Free ◽  
Chemical Potentials ◽  
Hydrophobic Nature ◽  
Mixing Schemes ◽  
Partial Molar Entropy ◽  
Partial Molar Enthalpies

In the preceding paper, we reported the values of model-free chemical potentials for aqueous methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 1-hexanol at 25°C over the entire compositional region. Using alcohol excess partial molar enthalpies, HEAL, determined earlier in this laboratory (Can. J. Chem. 74, 713 (1996)), we have calculated excess partial molar entropies for the alcohols, SEAL, where AL stands for an alcohol. We then calculated, numerically, the entropic interaction, SEAL–AL = N([Formula: see text]SEAL/[Formula: see text]nAL)p,T,nW, where nAL is the amount of AL, nW is the amount of H2O, and N is the total amount of solution. SEAL–AL signifies the effect of addition of AL upon the entropic situation of existing AL in solution. Using these quantities, the mixing schemes in aqueous alcohols have been studied. The earlier conclusions, which used HEAL and HEAL–AL alone, are confirmed. Furthermore, the order of the relative hydrophobic nature of alcohols is established from the behaviour of SEAL–AL and of HEAL–AL as methanol < ethanol < 2-propanol < 1-propanol. Key Words: aqueous alcohols, excess partial molar entropies, entropic interaction mixing schemes, hydrophobicity ranking.

scholarly journals Thermal expansivities of aqueous solutions of 2-butoxyethanol in the water-rich region: transition of mixing scheme

1992 ◽  
Vol 70 (10) ◽  
pp. 2659-2663 ◽  
Author(s):  
James V. Davies ◽  
Frankie W. Lau ◽  
Loanne T. N. Le ◽  
John T. W. Lai ◽  
Yoshikata Koga
Keyword(s):  
Free Energy ◽  
Aqueous Solutions ◽  
Gibbs Free Energy ◽  
Rich Region ◽  
Hydrophobic Solute ◽  
Thermal Expansivities ◽  
Mixing Schemes ◽  
Structure Enhancement ◽  
Derivatives Of ◽  
Transition Of Mixing Scheme

Thermal expansivities of aqueous solutions of 2-butoxyethanol (BE) were measured at concentrations of xBE < 0.04, where xBE is the mole fraction of BE. Thermal expansivity is a second derivative of the Gibbs free energy. The composition derivatives of thermal expansivities, the third derivatives, show peak anomalies at the same loci as the other third derivatives of the Gibbs free energy reported earlier from this laboratory (Can. J. Chem. 67, 671 (1989); J. Phys. Chem. 94, 3879 (1990); J. Phys. Chem. 95, 4119 (1991)). The loci of such anomalies form a boundary that separates two regions of totally different mixing schemes. The mixing scheme in the water-rich region seems to be consistent with the "iceberg formation," the "structure enhancement of H2O by hydrophobic solute," and the "hydrophobic attraction." In the intermediate composition region, the hydrogen bond network of H2O collapses due to the presence of too many molecules of BE, and H2O and BE molecules interact with each other as normal liquid molecules.

Ionic conductivity in the water-rich region of aqueous 2-butoxyethanol

1995 ◽  
Vol 73 (8) ◽  
pp. 1294-1297 ◽  
Author(s):  
Yoshikata Koga ◽  
Virginia J. Loo ◽  
Kataryna T. Puhacz
Keyword(s):  
Hydrogen Bond ◽  
Ionic Conductivity ◽  
Aqueous Solutions ◽  
Infinite Dilution ◽  
Ionic Conductivities ◽  
Molar Conductivity ◽  
Hydrogen Bond Network ◽  
Rich Region ◽  
Mixing Schemes ◽  
Bond Network

Ionic conductivities of HCl, KOH, and KCl were measured in aqueous solutions of 2-butoxyethanol (BE) at 25 °C. The quantity, Λj′ = σ/xj, which is almost proportional to the molar conductivity, was extrapolated to the infinite dilution xj → 0. σ is the conductivity and xj is the mole fraction of j(= HCl, KOH, or KCl). The plots of 0Λj′, the value of Λj′ extrapolated to infinite dilution, against xBE showed a change in slope at xBE = 0.0175. The previous work from this laboratory indicated that the mixing scheme changes qualitatively at the same locus, xBE = 0.0175. By mixing scheme we simply mean the way in which BE and H2O molecules mix with each other. Assuming additivity in 0Λj′ in terms of constituent ions, those values for H+OH− were calculated. Plots of [Formula: see text] thus calculated as a function of xBE in the water-rich region, 0 < xBE < 0.0175, suggest that the hydrogen bond probability decreases in the bulk of solution, as xBE increases. Keywords: aqueous 2-butoxyethanol, ionic conductivities, mixing schemes, hydrogen bond network.

scholarly journals Low-frequency Raman Spectroscopy of Aqueous Solutions of Aliphatic Alcohols

2001 ◽  
Vol 56 (8) ◽  
pp. 529-536 ◽  
Author(s):  
Koji Ydoshida ◽  
Toshio Yamaguchi
Keyword(s):  
Aqueous Solutions ◽  
Raman Spectra ◽  
Mole Fraction ◽  
Water Clusters ◽  
Pure Water ◽  
Low Frequency ◽  
Isosbestic Point ◽  
X Ray Diffraction ◽  
Alcohol Water ◽  
Solvent Clusters

Abstract Low-frequency Raman spectra have been measured at room temperature as functions of the alcohol mole fraction in aqueous solutions of methanol, ethanol, 1-propanol, 2 -propanol, and /er/-butylalcohol (TBA). Intrinsic Raman spectra R (ῡ) were obtained from depolarized Rayleigh wing spectra. Isosbestic points have been observed in R (ῡ) of the aqueous solutions of ethanol, 1-propanol, and 2 -propanol, suggesting that the structure o f the solutions is characterized by individual alcohol aggregates and water clusters without a significant amount of alcohol-water mixed aggregates. The R (ῡ) spectra have been expressed as R (ῡ ,x ) = w R (ῡ ,0 ) + aR(D, 1), where R(ῡ, 0) and R(ῡ, 1) are those for pure water and pure alcohols, respectively, and x is the mole fraction of alcohols. The coefficients w and a show the inflection points at characteristic alcohol mole fractions, where microhetrogeneity and structural transition of the solvent clusters take place, as previously shown by X-ray diffraction. In the aqueous solutions of methanol, where no microhetrogeneity takes place, no clear isosbestic point in R(ῡ) has been observed. For aqueous solutions of TBA, an isosbestic point in R(ῡ) has appeared when xTBA > 0.05. Two inflections points in the coefficients have been observed at xTBA « 0.1 and 0.35; the former composition corresponds to the transition composition from the TBA-TBA intermolecular contact to the TBA water molecular association, as previously reported by neutron diffraction.

scholarly journals Influence of Cross-Linking Degree on Hydrodynamic Behavior and Stimulus-Sensitivity of Derivatives of Branched Polyethyleneimine

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1085
Author(s):  
Alina Amirova ◽  
Tatyana Kirila ◽  
Mikhail Kurlykin ◽  
Andrey Tenkovtsev ◽  
Alexander Filippov
Keyword(s):  
Aqueous Solutions ◽  
Mole Fraction ◽  
Solution Temperature ◽  
Linear Polymers ◽  
Intermolecular Hydrogen Bonds ◽  
Critical Solution Temperature ◽  
Cross Linker ◽  
The Cross ◽  
Derivatives Of ◽  
Constant Characteristics

Cross-linked derivatives of acylated branched polyethyleneimine containing 2-isopropyl-2-oxazoline units were investigated in chloroform and aqueous solutions using methods of molecular hydrodynamics, static and dynamic light scattering, and turbidity. The studied samples differed by the cross-linker content. The solubility of the polyethyleneimines studied worsened with the increasing mole fraction of the cross-linker. Cross-linked polyethyleneimines were characterized by small dimensions in comparison with linear analogs; the increase in the cross-linker content leads to a growth of intramolecular density. At low temperatures, the aqueous solutions of investigated samples were molecularly dispersed, and the large aggregates were formed due to the dehydration of oxazoline units and the formation of intermolecular hydrogen bonds. For the cross-linked polyethyleneimines, the phase separation temperatures were lower than that for linear and star-shaped poly-2-isopropyl-2-oxazolines. The low critical solution temperature of the solutions of studied polymers decreased with the increasing cross-linker mole fraction. The time of establishment of the constant characteristics of the studied solutions after the jump-like change in temperature reaches 3000 s, which is at least two times longer than for linear polymers.

Thermodynamic properties of peptide solutions. The relative partial molar enthalpies of aqueous solutions of glycylglycylglycine, glycylglycylalanine and alanylglycylglycine

1983 ◽  
Vol 36 (9) ◽  
pp. 1813 ◽  
Author(s):  
MK Kumaran ◽  
ID Watson ◽  
GR Hedwig
Keyword(s):  
Thermodynamic Properties ◽  
Aqueous Solutions ◽  
Side Chain ◽  
Enthalpies Of Dilution ◽  
Flow Microcalorimetry ◽  
Water Side ◽  
Partial Molar Enthalpies

The enthalpies of dilution at 298 K of aqueous solutions of the tripeptides glycylglycylglycine, glycylglycylalanine and alanylglycylglycine have been determined by flow microcalorimetry. From these data the partial molar enthalpies of the solvent in the solutions have been calculated. The results indicate that water side-chain interactions make an important contribution to the solvation of peptides.

Thermodynamic Properties of Dilute Solutions of Hydrogen in Glassy PD.80SI.20

1981 ◽  
Vol 8 ◽  
Author(s):  
R.S. Finocchiaro ◽  
C.L. Tsai ◽  
B.C. Giessen
Keyword(s):  
Thermodynamic Properties ◽  
Composition Range ◽  
Volumetric Method ◽  
Vapor Pressures ◽  
Free Energies ◽  
Positive Deviation ◽  
Dilute Solutions ◽  
Maximum Value ◽  
Statistical Mechanical ◽  
Partial Molar Enthalpies

ABSTRACTEquilibrium vapor pressures of dilute solutions of hydrogen in glassy Pd.80Si.20 have been measured from 10–90°C and at hydrogen pressures P of 1–100 torr. Under these conditions the ratio of hydrogen to alloy, x as determined by a volumetric method, reaches a maximum value of 0.0070. Over this range of x, the system exhibits a positive deviation from Sieverts' Law; isotherms were analyzed in terms of Lacher's modified statistical mechanical theory of hydrogen in palladium. The data were used to calculate relative partial molar enthalpies, excess entropies, and excess free energies for the formation of the solid solutions. The thermodynamic properties were found to vary with hydrogen content over the composition range studied.

Mixed anion effect in sodium thiocyanate + sodium thiosulfate + water systems

1998 ◽  
Vol 76 (12) ◽  
pp. 1836-1843 ◽  
Author(s):  
G Kalita ◽  
N N Dass ◽  
S Mahiuddin
Keyword(s):  
Key Words ◽  
Mole Fraction ◽  
Sodium Thiosulfate ◽  
Water Systems ◽  
Sodium Thiocyanate ◽  
Anion Effect ◽  
Temperature Range

Densities and viscosities of R[xNaSCN + (1 - x)Na2S2O3] + (1 - R)H2O systems with R = 0.05, 0.10, 0.14, and 0.18 were measured as functions of mole fraction, x (= 0.0-1.0), and temperature (293.15 <= T/K <= 323.15). A significant mixed anion effect has been observed within the temperature range of the study. The normalized viscosity isotherms were found to detect the mixed anion effect ~1.2 to 3.7 times more than the simple viscosity isotherms. The progressive replacement of S2O32- ions by SCN- ions causes the systems to be less structured and S2O32- ions polarized Na+ ions more towards themselves than towards the SCN- ions. Both these effects govern the variation of the viscosity with mole fraction, x. The mixed anion effect was found to vanish at around R = 0.0106.Key words: mixed anion effect, sodium thiocyanate, sodium thiosulfate, viscosity.

scholarly journals Thermodynamic properties of 1-ethyl-3-methylimidazolium ethyl sulphate with nitrogen and sulphur compounds at T = (298.15 - 318.15) K and P = 1 bar

2016 ◽  
Author(s):  
◽  
Siyanda Brian Chule
Keyword(s):  
Refractive Index ◽  
Thermodynamic Properties ◽  
Binary Mixture ◽  
Binary Mixtures ◽  
Mole Fraction ◽  
Ethyl Acetoacetate ◽  
Binary Systems ◽  
Composition Range ◽  
Molar Refraction ◽  
The Ideal

In this work, the thermodynamic properties for the binary mixtures containing the ionic liquid (IL): 1-ethyl-3-methylimidazolium ethyl sulphate ([EMIM] [EtSO4]) were calculated. The binary systems studied were {pyridine (Py) or ethyl acetoacetate (EAA) or thiophene (TS) + [EMIM] [EtSO4]}. The results were interpreted in terms of the intermolecular interactions between the (pyridine + IL), (ethyl acetoacetate + IL), and (thiophene + IL) molecules. The physical properties: density, speed of sound, and refractive index were measured for the binary mixtures over the complete mole fraction range using an Anton Paar DSA 5000 M vibrating U- tube densimeter and an Anton Paar RXA 156 refractometer, respectively. The measurements were done at T = (298.15, 303.15, 308.15, 313.15, and 318.15) K and at p = 0.1 MPa. The experimental data was used to calculate the derived properties for the binary mixtures namely:- excess molar volume (V E ), isentropic compressibility (ks), molar refractions (R) and deviation in refractive index (Δn). For the binary mixtures, (Py or EAA or TS + IL), V E was negative throughout the whole composition range which indicates the existence of attractive intermolecular interaction between (pyridine + IL) and (ethyl acetoacetate + IL) for (thiophene + IL), V E was negative at low mole fraction of thiophene and became positive at high mole fraction of thiophene. For the binary mixtures (pyridine + IL), (ethyl acetoacetate + IL), ks was positive indicating that the binary mixtures were more compressible than the ideal mixture. For the binary mixture (thiophene + IL) ks was negative at low thiophene composition and positive at high composition indicating that the binary mixture was less compressible than the ideal mixture at low thiophene composition and more compressible at high composition of thiophene. The molar refraction, R, is positive for the (Py or EAA or TS + IL) binary systems at T = (298.15 – 318.15) K, molar refraction decreases as the organic solvent composition increases. For the binary mixture (pyridine + [EMIM] [EtSO4]), Δn is negative at mole fractions < 0.75 of pyridine and positive at mole fractions >0.75 at all temperatures and decreases with an increase in temperature. For the binary system (ethyl acetoacetate + [EMIM] [EtSO4]), Δn values are positive over the entire composition range and at all temperatures and increases with an increase in temperature. Δn values for the (thiophene + IL) system are negative for mole fractions of thiophene < 0.62 and becomes positive for mole fractions of thiophene > 0.62 and Δn increases with an increase in temperature. The Redlich-Kister smoothing equation was used successfully for the correlation of V E and Δn data. The Lorentz- Lorenz equation gave a poor prediction of V E , but a good prediction of density or refractive index.

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