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1.
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
2.
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
3.
Partial Molar Volumes of Some of α-Amino Acids in Binary Aqueous Solutions of MgSO4·7H2O at 298.15 K
The apparent molar volume, V
o
φ, 2, of glycine, alanine, α-amino-n-butyric acid, valine and leucine have been determined in aqueous solutions of 0.25, 0.5 and 1.0 mol⋅dm−3 magnesium sulfate, and the partial specific volume from density measurements at 298.15 K. These data have been used to calculate the infinite dilution apparent molar volume, V
o
2,m
, group contribution of amino acids and partial molar volume of transfer, Δtr
V
2,m
o, from water to aqueous magnesium sulfate solutions. The linear correlation of V
2,m
o for a homologous series of amino acids has been utilized to calculate the contributions of charged end groups (NH3
+, COO−), CH2 - groups and other alkyl chains of amino acids to V
2,m
o. The results for Δtr
V
2,m
o of amino acids from water to aqueous magnesium sulfate solutions have been interpreted in terms of ion-ion, ion-polar, hydrophilic-hydrophilic and hydrophobic-hydrophobic group interactions. The values of the standard partial molar volume of transfer for the amino acids with different hydrophobic contents, from water to aqueous MgSO4 are in general positive, indicating the predominance of the interactions of zwitterionic/hydrophilic groups of amino acids with ions of the salt. The hydration number decreases with increasing concentration of salt. The number of water molecules hydrated to amino acids decreases, further strengthening the predominance of ionic/hydrophilic interactions in this system. 相似文献
4.
The apparent molar volumes V
2,φ
, apparent molar isentropic compressibilities K
S,2,φ
, and enthalpies of dilution of aqueous glycine, alanine, α-amino butyric acid, valine, and leucine have been determined in aqueous 1.0 and 2.0 mol⋅dm−3 sorbitol solutions at 298.15 K. These data have been used to calculate the infinite dilution standard partial molar volumes
V2,m0V_{2,m}^{0}, partial molar isentropic compressibilities KS,2,m0K_{S,2,m}^{0}, and enthalpies of dilution Δdil
H
0 of the amino acids in aqueous sorbitol, along with the standard partial molar quantities of transfer of the amino acids from
water to aqueous sorbitol. The linear correlation of V2,m0V_{2,m}^{0} for this homologous series of amino acids has been utilized to calculate the contribution to V20V_{2}^{0} of the charged end groups (NH3+\mathrm{NH}_{3}^{+}, COO−), the CH2 group, and other alkyl chains of the amino acids. The results for the standard partial molar volumes of transfer, compressibilites
and enthalpies of dilution from water to aqueous sorbitol solutions have been correlated and interpreted in terms of ion–polar,
ion–hydrophobic, and hydrophobic–hydrophobic group interactions. A comparison of these thermodynamic properties of transfer
suggest that an enhancement of the hydrophilic/polar group interactions is operating in ternary systems of amino acid, sorbitol,
and water. 相似文献
5.
Viscosities and densities of sucrose in aqueous alkali metal halide solutions of different concentrations in the temperature
range 293.5 to 313.15 K have been measured. Partial molar volumes at infinite dilution (V
2
0
) of sucrose determined from apparent molar volume (φ
v
) have been utilized to estimate partial molar volumes of transfer (V
2,tr
0
) for sucrose from water to alkali metal halide solutions. The viscosity data of alkali metal halides in purely aqueous solutions
and in the presence of sucrose at different temperatures (293.15, 303.15 and 313.5 K) have been analysed by the Jones-Dole
equation. The nature and magnitude of solute-solvent and solute-solute interactions have been discussed in terms of the values
of limiting apparent molar volume (φ
v
0
), slope (S
v
) and coefficients of the Jones-Dole equation. The structure-making and structure-breaking capacities of alkali metal halides
in pure aqueous solutions and in the presence of sucrose have been ascertained from temperature dependence ofφ
v
0
. 相似文献
6.
Densities of solutions of tetramethyl-bis-urea (TMbU) or “Mebicarum” in H2O and D2O, with solute mole fraction concentrations (x
2) ranging up to 3.2 × 10−3, have been measured at 288.15, 298.15, 308.15 and 318.15 K using a precision vibrating-tube densimeter. The limiting apparent
molar volumes, V
φ,2
∞, and expansibilities, E
p, φ, 2
∞, of the solute have been calculated. The isotope effect δ V
φ,2
∞(H2O → D2O;T) is negative, monotonously decreases in magnitude with temperature and reverses sign at T ≈ 318 K. Water (H2O, D2O) and TMbU molecules in infinitely- and highly-dilute aqueous solutions form H(D)-bonded hydration complexes with a high packing density.
The hydration of TMbU should be treated as a superposition of two mechanisms, hydrophobic and hydrophilic, with the latter one predominating. 相似文献
7.
Dulal Chandra Kabiraz Tapan Kumar Biswas M. Entazul Huque 《Monatshefte für Chemie / Chemical Monthly》2010,39(11):1063-1068
Abstract
The apparent molar volumes (φ v) of KCl, KNO3, MgCl2, and Mg(NO3)2 have been determined in water and in aqueous sodium dodecylsulfate solutions from density measurements at 303.15, 308.15, 313.15, 318.15, and 323.15 K. The limiting apparent molar volumes (jv0 \varphi_{v}^{0} ) and experimental slopes (S v) were derived from the Masson equation. The partial molar volume transfer (\Updelta [`(V)]\texttr ) (\Updelta {\bar{V}}_{\text{tr}} ) of the electrolytes were obtained from limiting apparent molar volume data from water to aqueous sodium dodecylsulfate solutions and have been interpreted in terms of ion–ion, hydrophilic–hydrophilic, and hydrophobic–hydrophobic interactions on the basis of a co-sphere overlap model. It is shown that the transfer volumes (\Updelta [`(V)]\texttr ) (\Updelta {\bar{V}}_{\text{tr}} ) are positive and increase with increasing sodium dodecylsulfate concentration for all electrolytes. The structure making or breaking capacities of the electrolytes have been inferred from the sign of [∂2 φ v0/∂T 2]p, i.e., the second derivative of the limiting apparent molar volume with respect to temperature at constant pressure. In water, KCl and KNO3 exhibit structure breaking and MgCl2 and Mg(NO3)2 exhibit structure making behavior. All the studied electrolytes were found to act as structure makers in aqueous sodium dodecylsulfate solutions. 相似文献8.
The effect of an ionic liquid, 1-ethyl-3-methylimidazolium ethyl sulfate ([EMIm]ESO4), on the thermophysical properties of aqueous D-glucose solutions including density, viscosity, and electrical conductivity
have been investigated at 298.15 K. Using these properties, the apparent molar volumes, V
φ
, the viscosity B-coefficients and the molar conductivities, Λ
m, have been computed for the ternary D-glucose + [EMIm]ESO4+water solutions. The V
φ
values were used to calculate the standard partial molar volumes, Vf0V_{\phi}^{0}, and transfer volumes, DtrVf0\Delta_{\mathrm{tr}}V_{\phi}^{0}, of D-glucose from water to aqueous ionic liquid solutions. These volumetric parameters, for all the solutions studied, are
positive and increase monotonically with increasing the concentration of [EMIm]ESO4. These observations have been interpreted in terms of the interactions between D-glucose and ionic liquid in the aqueous
solution. The viscosity data were analyzed in terms of the Jones-Dole equation to determine the values of the viscosity B-coefficients. The calculated conductometric parameters, the limiting molar conductivities, Λ
0, the association constants, K
a, and the Walden products, Λ
0
η, for [EMIm]ESO4, decrease with increasing concentration of D-glucose. This trend suggests that the ions of an ionic liquid do not have the
same hydrodynamic size in the presence of D-glucose molecules (ILs) and consequently provides evidence for the dehydration
effect of the ionic liquid in aqueous D-glucose solutions. 相似文献
9.
The densities and speeds of sound for binary mixtures containing the solute ionic liquid (IL) methyltrioctylammonium bis(trifluoromethylsulfonyl)imide
([MOA]+[Tf2N]−), solute/solvent methanol, and solvent methyl acetate have been measured at 298.15, 303.15, 308.15 and 313.15 K at atmospheric
pressure. The binary mixtures studied are ([MOA]+[Tf2N]− + methyl acetate or methanol), and (methanol + methyl acetate). The apparent molar volume, V
φ
and the apparent molar isentropic compressibility, k
φ
, have been evaluated from the experimental density and speed of sound data, respectively. The parameters of a Redlich–Mayer
type equation were fitted to the apparent molar volume and apparent molar isentropic compressibility data. The apparent molar
volume and apparent molar isentropic compressibility at infinite dilution, Vf0V_{\phi}^{0} and kf0k_{\phi}^{0}, respectively, of the binary solutions have also been calculated at each temperature. The infinite dilution apparent molar
volume indicates that intermolecular interactions for (IL + methyl acetate) mixtures are stronger than for (IL + methanol)
mixtures at all temperatures except at 298.15 K, and that Vf0V_{\phi}^{0} for the (IL + methyl acetate or methanol) binary systems increases with an increase in temperature. For the (methanol + methyl
acetate) system the intermolecular interaction are weaker and Vf0V_{\phi}^{0} also increases with an increase in temperature. Values of the infinite dilution apparent molar expansibility, Ef0E_{\phi}^{0}, indicate that the interaction between (IL + methyl acetate) is greater than for (IL + methanol) and (methanol + methyl acetate). 相似文献
10.
The apparent molar volumes, V
φ
, of two series of homologous aliphatic carboxylic acids, H(CH2)
n
COOH [n=0–5] and (CH2)
n
(COOH)2 [n=0–5], were determined in dilute aqueous solutions by density measurements at T=298.15 K. Densities were measured using a vibrating-tube densimeter (DMA 5000, Anton Paar, Austria) at T=298.15 K. These results were used to calculate the apparent molar volumes of each solute over the concentration range 0.0050≤m/(mol⋅kg−1)≤0.3000. Values of the apparent molar volumes of undissociated acids Vf(u)0V_{\phi (u)}^{0} were also calculated. The variation of Vf(u)0V_{\phi (u)}^{0} was determined as a function of the aliphatic chain length of the studied carboxylic acids. 相似文献
11.
This paper reports the densities of aqueous solutions of the ionic liquid (IL) 1-methyl-3-pentylimidazolium tetrafluoroborate
([pmim][BF4]) that were measured from 278.15 to 343.15 K, at intervals of 5 K, using an Anton Parr model DMA 4500 oscillating U-tube
densitometer. The apparent molar volume,
φ
V
B, and the partial molar volume of [pmim][BF4],
, were calculated. The values of the apparent molar volume,
φ
V
B, were fitted to Pitzer’s model for volumetric properties by the method of least-squares, which allowed the partial molar
volume of the IL at infinite dilution,
, and Pitzer’s parameters, β
M,X
(0)V
and β
M,X
(1)V
, to be obtained. The small standard deviations of the fits show that Pitzer’s model is also appropriate for representing
the volumetric properties of aqueous solutions of the ionic liquid [pmim][BF4]. 相似文献
12.
The apparent molar volumes (V
φ
) of glycine, L-alanine and L-serine in aqueous 0 to 4 mol⋅kg−1 N-methylacetamide (NMA) solutions have been obtained by density measurement at 298.15 K. The standard partial molar volumes
(Vf0)V_{\phi}^{0}) and standard partial molar volumes of transfer (DtrVf0)\Delta_{\mathrm{tr}}V_{\phi}^{0}) have been determined for these amino acids. It has been show that hydrophilic-hydrophilic interactions between the charged
groups of the amino acids and the –CONH– group of NMA predominate for glycine and L-serine, but for L-alanine the interactions
between its side group (–CH3) and NMA predominate. The –CH3 group of L-alanine has much more influence on the value of DtrVf0\Delta_{\mathrm{tr}}V_{\phi}^{0} than that of the –OH group of L-serine. The results have been interpreted in terms of a co-sphere overlap model. 相似文献
13.
Kelei Zhuo Qiufen Zhang Xiaopeng Xuan Hucheng Zhang Jianji Wang 《Frontiers of Chemistry in China》2007,2(2):193-198
Densities have been measured for Glucose + HCl +Water at 10-degree intervals from 278.15 to 318.15 K. The apparent molar volumes
(V
Φ,G) and standard partial molar volumes (V
Φ,G
0
) for Glucose in aqueous solution of 0.2, 0.4, 0.7, 1.1, 1.6, 2.1 mol·kg−1 HCl have been calculated as well as volumetric interaction parameters (V
EG) for Glucose — HCl in water and standard partial molar expansion coefficients (∂V
Φ,G
0
/ ∂T)p. Results show that (1) the apparent molar volume for Glucose in aqueous HCl solutions increases lineally with increasing
molality of Glucose and HCl; (2) V
Φ,G/0 for Glucose in aqueous HCl solutions increases lineally with increasing molality of HCl; (3) the volumetric interaction parameters
for Glucose — HCl pair in water are small positive and vary slightly with temperature; (4) the relation between V
Φ,G
0
and temperature exists as V
Φ,G
0
= a
0 + a
1(T − 273.15 K)2/3; (5) values of (∂V
Φ,G
0
/ ∂T)p are positive and increase as temperatures rise, and at given temperatures decrease slightly with increasing molalities of
HCl, indicating that the hydration of glucose decreases with increasing temperature and molality of HCl. These phenomena are
interpreted successfully by the structure interaction model.
Translated from Acta Chimica Sinica, 2006, 64(16): 1635–1641 (in Chinese) 相似文献
14.
Yang-Xin Yu Tie-Zhu Bao Guang-Hua Gao Yi-Gui Li 《Journal of Radioanalytical and Nuclear Chemistry》1999,241(2):373-377
In order to obtain the exact information of atomic number density in the ternary system of HNO3−UO2(NO3)2−H2O, the densities were measured with an Anton-Paar DMA60/602 digital density meter thermostated at 298.15±0.01 K. The apparent
molal volumes for the systems were calculated from the experimental data. The present measured apparent molar volumes have
been fitted to the Pitzer ion-interaction model, which provides an adequate representation of the experimental data for mixed
aqueous electrolyte solutions up to 6.2 mol/kg ionic strength. This fit yields θ
V
, and ψ
V
, which are the first derivatives with respect to pressure of the mixing interaction parameters for the excess free energy.
With the mixing parameters θ
V
, and ψ
V
, the densities and apparent molar volumes of the ternary system studied in this work can be calculated with good accuracy,
as shown by the standard deviations. 相似文献
15.
Malyanah M. Taib Abobakr K. Ziyada Cecilia Devi Wilfred Thanapalan Murugesan 《Journal of solution chemistry》2012,41(1):100-111
Densities and refractive indices have been measured for binary mixtures of 1-propyronitrile-3-hexylimidazolium bromide + ethanol
in the temperature range 293.15–323.15 K. From the experimental data the excess molar volume V
E, refractive index deviation Δn
D, and the coefficient of thermal expansion α were calculated and fitted to fifth- and third-order Redlich–Kister type equations, respectively. Using the measured densities,
the apparent molar volumes (V
ϕ
), limiting apparent molar volumes (Vf0V_{\phi}^{0}) and limiting apparent molar expansivities (Ef 0E_{\phi} ^{0}) were also determined and the details are discussed. 相似文献
16.
Isabel Bandrés Sandra Meler Beatriz Giner Pilar Cea Carlos Lafuente 《Journal of solution chemistry》2009,38(12):1622-1634
Aggregation of the ionic liquids 1-butylpyridinium tetrafluoroborate, 1-butylpyridinium triflate, 1-butyl-2-methylpyridinium
tetrafluoroborate, 1-butyl-3-methylpyridinium tetrafluoroborate, 1-butyl-4-methylpyridinium tetrafluoroborate, 1-butyl-3-methylpyridinium
dicyanamide, and 1-octyl-3-methylpyridinium tetrafluoroborate in aqueous solution has been characterized at 298.15 K through
density, ρ, speed of sound, u, and conductivity, σ, measurements. In addition, apparent molar volumes, V
φ
, and isentropic compressibilities, κ
s
, have been calculated from the experimental data. To characterize the formation of aggregates, the critical aggregation concentration
of the ionic liquids, cac, the degree of ionization of the aggregates, β, and the standard Gibbs energy of aggregation, DGm°\Delta G_{\mathrm{m}}^{\circ}, have been obtained, with good agreement between results derived from the different methods. The dependence on the structural
variation of these ions has been analyzed by comparing the results obtained for this series of ionic liquids. 相似文献
17.
Hemayat Shekaari Abolfazl Bezaatpour Rasoul Elhami 《Journal of solution chemistry》2012,41(3):516-524
The apparent molar volumes and viscosities of N,N′-bis(salicylaldehyde)-1,3-diaminopropane Schiff base (Salpr) have been determined in ionic liquid {1-pentyl-3-methylimidazolium
bromide ([PnMIm]Br)} + N,N-dimethylformamide (DMF) solutions at 298.15 K from density and viscosity measurements using a vibrating tube densimeter and
übbelohde type viscometer, respectively. These data have been used to calculate standard partial molar volumes, Vf 0V_{\phi} ^{0}, transfer partial molar volumes, Δtr
V
0, and viscosity B-coefficients of the solutions. The transfer partial molar volumes are negative, and decrease with increasing the concentration
of ionic liquid for all of the investigated solutions. It found that this ionic liquid interacts strongly with the Schiff
base (Salpr) and has desolvation effect on the Schiff base molecules. 相似文献
18.
Mohammad M. H. Bhuiyan Andrew W. Hakin Jin Lian Liu 《Journal of solution chemistry》2010,39(6):877-896
Apparent molar volumes (V
2,φ
) and heat capacities (C
p2,φ
) of glycine in known concentrations (1.0, 2.0, 4.0, 6.0, and 8.0 mol⋅kg−1) of aqueous formamide (FM), acetamide (AM), and N,N-dimethylacetamide (DMA) solutions at T=298.15 K have been calculated from relative density and specific heat capacity measurements. These measurements were completed
using a vibrating-tube flow densimeter and a Picker flow microcalorimeter, respectively. The concentration dependences of
the apparent molar data have been used to calculate standard partial molar properties. The latter values have been combined
with previously published standard partial molar volumes and heat capacities for glycine in water to calculate volumes and
heat capacities associated with the transfer of glycine from water to the investigated aqueous amide solutions, D[`(V)]2,tro\Delta\overline{V}_{\mathrm{2,tr}}^{\mathrm{o}} and D[`(C)]p2,tro\Delta\overline{C}_{p\mathrm{2,tr}}^{\mathrm{o}} respectively. Calculated values for D[`(V)]2,tro\Delta\overline{V}_{\mathrm{2,tr}}^{\mathrm{o}} and D[`(C)]p2,tro\Delta\overline{C}_{p\mathrm{2,tr}}^{\mathrm{o}} are positive for all investigated concentrations of aqueous FM and AM solutions. However, values for D[`(C)]p2,tro\Delta\overline{C}_{p\mathrm{2,tr}}^{\mathrm{o}} associated with aqueous DMA solutions are found to be negative. The reported transfer properties increase with increasing
co-solute (amide) concentration. This observation is discussed in terms of solute + co-solute interactions. The transfer properties
have also been used to estimate interaction coefficients. 相似文献
19.
Densities of NaOH(aq) solutions with molalities between 0.033 and 6.047 mol⋅kg−1 were measured with a vibrating-tube densitometer at temperatures between 373 K and 623 K and pressures from near the saturation vapor pressure of water to 30 MPa. Apparent molar volumes, V
φ, calculated from the measured densities in this work were well represented with the Pitzer ion-interaction treatment up to T = 523 K. Above that temperature the formation of ion pairs must be taken into account to describe correctly the molality dependence of V
φ and for the reliable extrapolation of V
φ to infinite dilution. Standard-state thermodynamic properties for the ion formation reaction were taken from recently published electrical conductivity measurements. A comparison with previous correlations of volumetric properties of NaOH(aq) is presented covering the full range of pressure and temperature. 相似文献
20.
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