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1.
Density (ρ), viscosity (η), and surface tension (γ) for 0.005–0.25 mol ⋅ kg−1 solutions of urea, 1-methylurea, and 1,3-dimethylurea solutions have been measured at intervals of 0.005 mol ⋅ kg−1. Apparent molal volume (V
o, cm3 ⋅ mol−1) and intrinsic viscosity coefficients (B and D) are calculated from the ρ and η values, respectively. Primary data were regressed and extrapolated to zero concentration for the limiting density (ρ
0), apparent molal volume (V
φ
0), viscosity (η
0), and surface tension (γ
0) values for solute–solvent interactions. The –CH3 (methyl) groups of N-methylureas weaken hydrophilic interactions and enhance hydrophobic interactions, and the values of the ρ
0 and V
φ
o reflect the intermolecular forces due to electrostatic charge, whereas the η
0 and γ
0 values reflect the frictional and surface forces. The B values depict the size of hydrodynamic sphere due to heteromolecular forces whereas D shows the effect of concentration. The molar surface energy (ΔE
m/sur) for dropwise flow was calculated from the γ values and decreases with concentration and temperature, but increases with –CH3 weakening of the hydrophilic interactions and strengthening the hydrophobic interactions. 相似文献
2.
Excess Molar Volume and Viscosity of Isobutyric Acid + Water Binary Mixtures Near and Far Away from the Critical Temperature 总被引:1,自引:0,他引:1
The excess molar volume VE, shear viscosity deviation Δη and excess Gibbs energy of activation ΔG∗E of viscous flow have been investigated by using density (ρ) and shear viscosity (η) measurements for isobutyric acid + water (IBA+W) mixtures over the entire range of mole fractions at five different temperatures,
both near and close to the critical temperature (2.055K ≤ (T−Tc)≤ 13.055K). The results were also fitted with the Redlich–Kister equation. This system exhibited very large negative values
of VE and very large positive values of Δη due to increased hydrogen bonding interactions and correlation length between unlike molecules in the critical region and
to very large differences between the molar volumes of the pure components at low temperatures. The activation parameters
ΔH∗ and ΔS∗ have been also calculated and show that the critical region has an important effect on the volumetric properties. 相似文献
3.
M. N. Roy R. Chanda G. Ghosh 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(8):1331-1341
The densities (ρ) and viscosities (η) for the ternary liquid mixtures of water + N,N-dimethylformamide + monoalkanols, have
been measured as a function of the composition at 298.15, 308.15, and 318.15 K. From the experimental measurements excess
molar volumes (V
E), Viscosity deviation (Δη), and synergy index (I
s) have been evaluated. The speeds of sound have been also measured and excess isentropic compressibilities (K
sE) are calculated al 298.15 K. The results are discussed and interpreted in terms of molecular package and specific interaction
predominated by hydrogen bonding, been investigated. 相似文献
4.
By the method of dissolution calorimetry integral enthalpies of dissolution Δsol
H
m of L-serine are measured in the mixtures of water with glycerol, ethylene glycol, and 1,2-propylene glycol at the concentration
of the organic solvent up to 0.42 mole fraction. The standard values of enthalpies of dissolution (Δsol
H
0) and transfer (Δtr
H
0) of amino acids from water to mixed solvents are calculated. The calculated values of the enthalpy coefficients of pair interactions
of L-serine with the molecules of co-solvents are positive. The data obtained are interpreted in terms of prevalence of different
types of interactions in solutions and the influence of nature of co-solvents on the thermochemical characteristics of the
dissolved amino acids. 相似文献
5.
V. G. Badelin I. N. Mezhevoi 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(6):934-937
Integral enthalpies of dissolution Δsol
H
m
of L-cysteine in mixtures of water with glycerol, ethylene glycol, and 1,2-propylene glycol at concentrations of organic
solvents of up to 0.37 mole fraction were measured by calorimetry of dissolution. The standard values of the dissolution enthalpies
(Δsol
H°) and the transfer enthalpies (Δtr
H°) of amino acid from water to the mixed solvent were calculated. It was shown that the calculated enthalpic coefficients
of the pair interactions of L-cysteine with cosolvent molecules have positive values. The obtained data are interpreted from
the viewpoint of the prevalence of different types of interactions in the solutions and influence of the cosolvents nature
on the thermochemical characteristics of amino acid dissolution. 相似文献
6.
Parimal C. Dey Muhammad A. Motin Tapan K. Biswas Entazul M. Huque 《Monatshefte für Chemie / Chemical Monthly》2003,37(2):797-809
The apparent molar volume (φv) and viscosity (η) of L(+)-arabinose, D(+)-galactose, D(−)-fructose, D(+)-glucose, sucrose, lactose, and maltose in water and in 0.1% and 0.3% water-Surf Excel solutions were measured as a function of solute concentrations at 308.15, 313.15, and 323.15 K, respectively. The apparent molar volume (φv) of the carbohydrates was found to be a linear function of the concentration. From a φv versus molality (b) plot, the apparent molar volume at infinite dilution (), which is practically equal to the partial molar volume at infinite dilutions () of these substances was determined. The viscosity coefficients B and D for the carbohydrates were calculated on the basis of the viscosity of the solutions and the solvent using the Jones-Dole equation. The activation free energy for viscous flow (ΔG ≠) of the solutions was also calculated using the Eyring equation. The carbohydrates showed structure making behaviour both in water and in water-Surf Excel solutions. When water-Surf Excel solutions and pure water solutions containing carbohydrate molecules are compared, the former were found to be more structured. The behaviour of these solutes in water and in water-Surf Excel solution systems is discussed in the light of solute–solvent interactions. 相似文献
7.
The conductance behaviour of HCl in water-ethylene glycol, water-diethylene glycol and ethylene glycol-diethylene glycol mixtures
was investigated in the complete range of solvent compositions of 25°C by applying the three-parameter conductance equation.
No appreciable association of the acid was observed in any of the mixed solvents. The large decrease ofΛ
0 andΛ
0
η
0 of the acid in the early and end composition region of the mixed solvents has been attributed to the drastic structural changes
brought about by the addition of the organic component in the aqueous solvent mixtures and by the addition of diethylene glycol
in the case of ethylene glycol-diethylene glycol mixtures. 相似文献
8.
The viscosity deviation (Δη), the excess molar volume (V
E) and the ultrasonic speed (u) have been investigated from viscosity (η) and density (ρ ) measurements of binary liquid mixtures of 1,2-dimethyoxyethane with methanol, ethanol, propan-1-ol, butan-1-ol,
pentan-1-ol, hexan-1-ol or octan-1-ol over the entire range of composition at 298.15 K. The excess volumes are negative over
the entire range of composition for all of the mixtures with the exception of hexan-1-ol and octan-1-ol. The excess isentropic
compressibilities (K
S
E) and viscosity deviations are negative for all of the mixtures. The magnitudes of the negative values of V
E decrease with the number of carbon atoms of the alkan-1-ol. The trend of increasing K
S
E values with the chain length of the alkanol is similar to that observed in the case of V
E. Graphs of V
E, Δ η, K
S
E, Δ u, L
f
E and Z
E against composition are presented as a basis for a qualitative discussion of the results. 相似文献
9.
Parimal C. Dey Muhammad A. Motin Tapan K. Biswas Entazul M. Huque 《Monatshefte für Chemie / Chemical Monthly》2003,134(6):797-809
Summary. The apparent molar volume (φv) and viscosity (η) of L(+)-arabinose, D(+)-galactose, D(−)-fructose, D(+)-glucose, sucrose, lactose, and maltose in water and in 0.1% and 0.3% water-Surf Excel solutions were measured as a function
of solute concentrations at 308.15, 313.15, and 323.15 K, respectively. The apparent molar volume (φv) of the carbohydrates was found to be a linear function of the concentration. From a φv versus molality (b) plot, the apparent molar volume at infinite dilution (), which is practically equal to the partial molar volume at infinite dilutions () of these substances was determined. The viscosity coefficients B and D for the carbohydrates were calculated on the basis of the viscosity of the solutions and the solvent using the Jones-Dole equation. The activation free energy for viscous flow (ΔG
≠) of the solutions was also calculated using the Eyring equation. The carbohydrates showed structure making behaviour both in water and in water-Surf Excel solutions. When water-Surf
Excel solutions and pure water solutions containing carbohydrate molecules are compared, the former were found to be more
structured. The behaviour of these solutes in water and in water-Surf Excel solution systems is discussed in the light of
solute–solvent interactions.
Corresponding author. E-mail: chemistry_ru@yahoo.com
Received March 19, 2002; accepted (revised) July 31, 2002
Published online February 24, 2003 相似文献
10.
Densities (ρ) of glycine, L-alanine, and L-valine in aqueous solutions of MgCl2-6H2O (0.1-0.8 mol kg-1) have been measured at 288.15, and 308.15 K. Apparent molar volumes (V
φ), and limiting partial molar volumes (V
φ
0
) of each amino acid have been calculated. These data were combined with the earlier reportedV
φ
0
values of glycine, L-alanine, and L-valine in aqueous MgCl2·6H2O solutions at 298.15 K in order to describe the temperature dependence behaviour of partial molar quantities. Group contributions
to partial molar volumes have been determined for the amino acids. The trends of transfer volumes (△V
φ
0
) have been interpreted in terms of solute-cosolute interactions on the basis of a cosphere overlap model. Pair and triplet
interaction coefficients have also been calculated from transfer parameters. 相似文献
11.
The excess molar volume (V E), viscosity deviations (Δη) and Gibbs excess energy of activation for viscous flow (G∗E) have been investigated from density (ρ) and viscosity (η) measurements of eight binary mixtures of 1,3-dioxolane with methanol,
ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, and i-amyl alcohol over the entire range of mole fractions at 303.15 K. The viscosity data have been correlated with the Grunberg
and Nissan equation. Furthermore, excess isentropic compressibilities (KSE) have been calculated from ultrasonic speed measurements of these binary mixtures at 303.15 K. The deviations have been fitted
by a Redlich–Kister equation and the results are discussed in terms of molecular interactions and structural effects. The
excess properties are found to be either negative or positive depending on the molecular interactions and the nature of the
liquid mixtures. The systems studied exhibit very strong cross association through hydrogen bonding. 相似文献
12.
Ufuk Sancar Vural Fatih Durmaz Ozcan Kocyigit Hasan Kocyigit V. Muradoglu Beril Akin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(13):2260-2268
Excess molar volumes (V
E), viscosities, refractive index, and Gibbs energies were evaluated for binary biodiesel + benzene and toluene mixtures at
298.15 and 303.15 K. The excess molar volumes V
E were determined from density, while the excess Gibbs free energy of activation G*E was calculated from viscosity deviation Δη. The excess molar volume (V
E), viscosity deviation (Δη), and excess Gibbs energy of activation (G*E) were fitted to the Redlich-Kister polynomial equation to derive binary coefficients and estimate the standard deviations
between the experimental data and calculation results. All mixtures showed positive V
E values obviously caused by increased physical interactions between biodiesel and the organic solvents. 相似文献
13.
Density of the water-ethylene glycol binary mixtures was measured in the entire range of compositions in the temperature range
278–333.15 K (6 values) at atmospheric pressure using a vibration densimeter. Mixtures with low concentrations of ethylene
glycol were studied at 15 temperatures in the range of 274–333.15 K. Excess molar volumes V
m
E
, the partial molar volumes of water -V
1 and ethylene glycol, -V
2, the coefficients of thermal volume expansion α of the mixture, the partial molar volume coefficients of thermal expansion
of water $
\bar V_1
$
\bar V_1
and ethylene $
\bar V_2
$
\bar V_2
were calculated. Excess molar volumes were described using the Redlich-Kister equation. The density ρ of the mixture was
found to increase with the increasing ethylene glycol concentration at all temperatures, but at low content of ethylene glycol
the dependence ρ = f(T) of the mixture at ∼276.5 K passed through a maximum. The coefficient α increases sharply in the composition range 0 <
x < 0.2, in the range 0.5 < x <1 remains almost unchanged, and at T > 277 K is positive for all compositions. The dependences $
\bar \alpha _1
$
\bar \alpha _1
= f (x) and $
\bar \alpha _2
$
\bar \alpha _2
= f (x) are complex in whole temperature range and are characterized by the presence of an extremum. V
m
E
values are negative at all temperatures, and upon increase in the temperature the deviation from ideality decreases (x is the mole fraction of ethylene glycol). 相似文献
14.
Abbas Ali Rostami Mohammad Javad Chaichi Mostafa Sharifi 《Monatshefte für Chemie / Chemical Monthly》2007,138(10):967-971
Summary. Density (ρ) and viscosity (η) values of the binary mixtures of DMP + 1-pentanol, 1-butanol, and 1-propanol over the entire range of mole fraction at 298.15 and 303.15 K were measured in atmospheric
pressure. The excess molar volume (V
E), viscosity deviations (Δη), and excess Gibbs energy of activation for viscous flow (G*E) were calculated from the experimental measurements. These results were fitted to Redlich–Kister polynomial equation to estimate the binary interaction parameters.
The viscosity data were correlated with equations of McAllister. The calculated functions have been used to explain the intermolecular interaction between the mixing components. 相似文献
15.
Man Singh 《Journal of Chemical Sciences》2006,118(3):269-274
Fundamental properties, density (ρ) and viscosity (η), of citric acid (CA) and disodium hydrogen orthophosphate (DSP) at various
strengths were obtained at different temperatures. The ρ and η values were used to determine apparent molal volumes and viscosity
of systems. The ρ, VΦ and η values were regressed against molalitym for ρ0, η0 and V
Φ
0
, the limiting constants at infinite dilution (m → 0) for ionic and molecular interactions. The ρ0 and V
Φ
0
of aq. acids are higher than those of aq. DSP and the viscosity of DSP is higher than that of aq. CA. Examination of ρ0 and V
Φ
0
functions indicates that mutual compositions of CA and DSP counterbalance concentration and temperature effects on pH in
bioprocesses. 相似文献
16.
The apparent molar volumes, V
φ
, of glycine, L-alanine and L-serine were obtained in aqueous 0 to ∼4 mol⋅kg−1 N,N-dimethylacetamide (DMA) solutions from density measurements at 298.15 and 308.15 K. The standard partial molar volume,
V
φ
o, and standard partial molar volumes of transfer, Δtr
V
φ
o, were determined for these amino acids. It has been shown that hydrophilic-hydrophilic interactions between charged groups
of the amino acids and the —CON= group of DMA are predominant in the case of glycine and L-serine, but for L-alanine the interactions
between its side group (—CH3) and DMA are predominant. An increase in temperature increases the standard partial molar volumes but decreases the transfer
volumes of the amino acids. The results have been interpreted in terms of cosphere overlap model. 相似文献
17.
The electric constant (ɛ′) and dielectric loss (ɛ″) for dilute solutions of sulfolane in benzene solution has been measured
at 9.885 GHz at different temperatures (25, 30, 35, and 40°C) by using standard microwave techniques. Following the single
frequency concentration variational method, the dielectric relaxation time (τ) and dipole moment (μ) have been calculated.
It is found that dielectric relaxation process can be treated as the rate process, just like the viscous flow. Based on the
above studies, monomer structure of sulfolane in benzene has been inferred. The presence of solute-solvent associations in
benzene solution has been proposed. Energy parameters (ΔH
ɛ, ΔF
ɛ, ΔS
ɛ) for dielectric relaxation process of sulfolane in benzene at 25, 30, 35, and 40°C have been calculated and compared with
the corresponding energy parameters (ΔH
η, ΔF
η, ΔS
η) for the viscous flow. 相似文献
18.
Felipe Gómez-de la Torre Yolanda Gutiérrez Félix A. Jalón Blanca R. Manzano Ana Rodríguez 《Monatshefte für Chemie / Chemical Monthly》2000,35(5):1267-1280
Partial removal of chloride anions from the dimer [Pd(η3-2-CH3*C3H4)(μ-Cl)]2 with AgTf(Tf = CF3SO3) followed by addition of dppm affords [Pd2(η3-Me*C3H4)2(μ-Cl)(μ-dppm)]Tf (1). The substitution of Cl− by X− (X = pz, SC6F5, S py ) using the appropriate salts yields the new derivatives [Pd2(η3-Me*C3H4)2(μ-X)(μ-dppm)]Tf (2–4). All complexes exhibit a dinuclear half-A-frame structure with two isomers present in solution. The isomers differ in the relative orientation of the two allyl groups (cis or trans). The isomer interconversion was studied by variable temperature 1H NMR spectroscopy. The molecular structures of 2 and 4 were solved by X-ray diffraction studies. A distorted boat conformation of the seven- or six-membered metallacycle was found in both cases. 相似文献
19.
Shear viscosity deviations Δη have been investigated by using density (ρ) and kinematic viscosity (ν) measurements for isobutyric acid + water (IBA + W) mixtures over the entire range of mole fractions at atmospheric pressure
and at two temperatures (301.15 and 315.15 K). This study extends the temperature range from the five other temperatures investigated
in a previous work, 1.055 K≤(T−T
c
)≤14.055 K, both far from and close to the critical temperature. This system exhibits very large positive values of Δη due to increased hydrogen bonding interactions and the correlation length between unlike molecules in the critical region,
and to very large differences between the molar volumes of the pure components at low temperatures. The results were also
fitted with the Redlich–Kister polynomial equations and the recently proposed Herráez correlation equation. Comparisons between
the two models at different temperatures and number of parameters are discussed. We note that, in this system where the shear
viscosity η as a function of mole fraction (x
1) of IBA presents a maximum, experimental data are in agreement with the two correlation models when more than three parameters
are employed, especially for temperatures far from the critical temperature. 相似文献
20.