Molar Volumes Of Mixing Research Articles

A Volumetric Study of Tetracaine Hydrochloride in Aqueous and in Aqueous Electrolyte Solutions at Different Temperatures

The experimental densities of a local anesthetical drug, tetracaine hydrochloride (TC·HCl) in aqueous binary (H2O + TC·HCl) solutions and aqueous ternary electrolytic solutions (H2O + NaCl/KCl + TC·HCl) are reported at 288.15, 293.15, 298.15, 303.15 and 308.15 K in the dilute concentration region. The densities, were used to calculate apparent molar volumes ( $$V_{\phi }$$ ) at the finite concentrations of TC·HCl at the studied temperatures. The coefficient of thermal expansion (α) of solutions and the apparent molar expansivity ( $$E_{\phi }$$ ) of the solute, at 293.15, 298.15 and 303.15 K are also obtained. The limiting apparent molar volume ( $$V_{\phi }^{0}$$ ) and limiting apparent molar expansivity ( $$E_{\phi }^{0}$$ ) of TC·HCl were estimated using extrapolation methods. It is noted that the solute expansivity goes through a minimum in water as a function of temperature and at lower concentrations of electrolytes. By using the $$V_{\phi }^{0}$$ data of the studied binary and ternary systems, the values of transfer volumes, that is, volume changes due to transfer ( $$\Delta_{{{\text{tr}}}} V_{\phi }^{0}$$ ) from aqueous to mixed electrolyte solutions, are estimated. The observed $$\Delta_{{{\text{tr}}}} V_{\phi }^{0}$$ values are found to be both temperature and concentration dependent. The excess molar volume of mixing ( $$\Delta_{\text{m}} V^{{\text{E}}}$$ ) are also calculated at 298.15 K. The volume changes due to micellization are small and the sign and magnitude depend upon the structure making and breaking abilities of the salt. It is suggested that the micelles involved are of the stacking type and not in the form of linear aggregates. The hydration shell water structure around the cations seems to be controlled by temperature and the nature of the perturbing ions. The results are explained in terms of unique stacking type interaction, akin to micelles but differing in details on the mode of interactions.

Modelling the density of Al2O3–CaO–MgO–SiO2 system using the CALPHAD approach

The density of Al2O3–CaO–MgO–SiO2 system is calculated using a model for molar volume. The model is similar to the one used for enthalpy of a multicomponent solution in the CALPHAD approach. The expression for molar volume consists of two terms: one representing the volume contribution from pure components and the other the volume of mixing. The molar volume of mixing takes into account of the binary and the ternary interactions. A total of 565 experimental density data for the constituent unary, binary and ternary systems were collected from the literature. These were used as input to simultaneously optimise the model parameters describing the molar volume, after ensuring that the data belong to a fully molten state. During the optimisation 48 data points that showed significant deviation from the average trend were excluded. The optimised model parameters for the unary, binary and ternary subsystems were used to calculate the density of the quaternary system. The calculated results were compared with experimental data. Finally, it is shown that the volume of mixing of binary systems correlates well with the corresponding enthalpy of mixing.

On the composition dependence of the microscopic structure, thermodynamic, dynamic and dielectric properties of water-dimethyl formamide model mixtures. Molecular dynamics simulation results

Isothermal-isobaric molecular dynamics simulations have been performed to examine an ample set of properties of the model water-N,N-dimethylformamide (DMF) mixture as a function of composition. The SPC-E and TIP4P-Ew water models together with two united atom models for DMF [Chalaris M., Samios J., J. Chem. Phys., 2000, 112, 8581; Cordeiro J., Int. J. Quantum Chem., 1997, 65, 709] were used. Our principal analyses concern the behaviour of structural properties in terms of radial distribution functions, and the number of hydrogen bonds between molecules of different species as well as thermodynamic properties. Namely, we explore the density, excess mixing molar volume and enthalpy, the heat capacity and excess mixing heat capacity. Finally, the self-diffusion coefficients of species and the dielectric constant of the system are discussed. In addition, surface tension of water-DMF mixtures has been calculated and analyzed.

Volumetric properties of 2,5-dimethylfuran in mixtures with octane or dodecane from 293 K to 393 K and pressures up to 70 MPa

We report isothermal volumetric properties for two binary systems constituted by 2,5-dimethylfuran (x)+a linear alkane (1−x); octane and dodecane are the representative alkanes. Compressed liquid densities were obtained via oscillating period measurements in two commercial vibrating U-shaped tube densimeters. The experiments were performed within the pressure and temperature intervals from 0.1MPa to 70MPa and from 293K to 393K, respectively. Properties for these binary systems were measured at x=(0.1154, 0.2999, 0.4967, 0.6962, 0.8924) for 2,5-dimethylfuran+octane mixtures; whereas, compositions measured for 2,5-dimethylfuran+dodecane mixtures were x=(0.1995, 0.4067, 0.4972, 0.6053, 0.8045). Experimental density data were correlated by using the Tammann-Tait equation. Thermodynamic derived properties were calculated from the same equation, and their dependence on pressure, temperature and composition was discussed. These properties were isobaric thermal expansivity, isothermal compressibility, thermal pressure coefficient, internal pressure and mixing molar volume.

Calculation for density of molten slags using optical basicity

A model for density calculation of multicomponent slags was developed in the present work. This model is an extension of a previous model proposed by the present author. Density values of molten slags were calculated from molar volume values, which were calculated from molar volume of pure component and mixing molar volume. Mixing molar volume is correlated to differences between reciprocals of optical basicities of network forming oxides and those of network modifying oxides. Charge compensation for AIO45− was taken into consideration explicitly. An increase in molar volume due to Al coordination shift from sixfold to fourfold was modelled by defining molar volume of a hypothetical state of alumina in fourfold coordination in the present work. Density values of M2O–SiO2 (M = Na, K), CaO–Na2O–SiO2, MgO–Na2O–SiO2, Al2O3–CaO–SiO2, Al2O3–Na2O–SiO2 and Al2O3–CaO–MgO–SiO2 system were calculated by employing the present model. Comparisons between calculated and experimental values in literature were also made. The calculated values are in good agreement with experimental data with a mean deviation within 2%. The present work also showed that the addition of network modifying oxide with high optical basicity values would lead to a remarkable negative deviation of molar volume from ideal mixing, which could be interpreted by considering larger Si–O shortening caused by metal cations with lower electronegativity. In addition, the positive deviation for metal oxide and alumina join was also well explained in terms of molar volume increase due to Al coordination change in the present work.

Thermodynamic properties of aqueous solutions of pyridine and piperidine

This research was designed to examine the thermodynamic properties of aqueous solutions of pyridine and piperidine. The density, excess molar enthalpy of mixing, H E, and excess molar volume of mixing, v E of piperidine–water and pyridine–water mixtures were studied at three temperatures, ranging from 294 K to 315 K. The H E and v E are negative for both mixtures, minimizing at a water mole fraction of about 0.55. The minimum H E for piperidine–water mixtures is −2.23 kJ/mol which is compared with −1.63 kJ/mol for pyridine–water mixtures. The minimum v E are about −1.7 cm 3/mol and −0.7 cm 3/mol for piperidine–water and pyridine–water mixtures, respectively. The thermal expansion coefficients α T at 303 K, calculated from the density studies, exhibited significant positive deviations (about 20%) from ideality for piperidine–water mixtures. In contrast to this pyridine–water α T only exhibited small positive deviations from ideality of about 2%. The results predict decreases in the absolute magnitude of v E with an increase in temperature which are 5. × 10 −3 cm 3/K mol and 1. × 10 −3 cm 3/K mol, for piperidine–water and pyridine–water mixtures, respectively. The results for v E for piperidine–water mixtures agree with the very precise work of Afzal et al., J. Chem. Thermodyn. 40 (2008) 47–53. The data are interpreted in terms of the greater number of opportunities for hydrogen bonding interactions between the unlike molecules for the piperidine–water mixtures.

Mixing Molar Volume of Liquid n- and i-Alkanes Based on the Law of Corresponding States with Potential between Functional Groups

The excess Helmholtz free energy of a liquid alkane mixture is expanded around that of a reference liquid, the pair potential of which is the sum of a hard-sphere potential and an attractive potential, with the difference between the potentials. The characteristic length of the mixture is chosen such that the first-order perturbation term vanishes. The molar volume of the mixture reduced by the characteristic length is expressed by the sum of those of the reference and the second-order perturbation term in the corresponding states. The equation of the mixing molar volume is expressed by the corresponding states equations of the mixture and the pure components with the characteristic length and energy without any binary interaction parameters and reproduces the observed mixing molar volume well. The characteristic parameters are expressed by the parameters of the potential between the functional groups in the molecules, which are not fluid specific.

Mixing Properties of Unsymmetrical Molten Salts Based on the Law of Corresponding States

The law of corresponding states of molten salt mixtures that include unsymmetrical salts was developed. The corresponding states equations for the thermodynamic and transport properties were obtained by expanding the Helmholtz free energy and the transport properties in terms of differences of the pair potential parameters, difference of the ionic size, and difference of the ionic mass. The effect of valences on the properties was accounted for by the products of cation and anion valences in the corresponding states equations. Equations for the mixing molar volume, surface tension, electrical conductivity, and viscosity were derived from the corresponding states equations. The estimated mixing properties satisfactorily agreed with the observed ones.

Composition dependence of densities and excess molar volumes of mixing of C 8C 15 n-alkane binary liquid systems at 308.15 and 313.15 K

The densities and excess molar volumes of eight n-alkane binary liquid systems: n-octane—n-undecane; n-octane—n-tetradecane; n-octane—n-pentadecane; n-decane—n-pentadecane; n-undecane—n-pentadecane; n-tridecane—n-pentadecane; n-decane—n-tridecane; n-undecane—n-tridecane were determined over the entire composition range at 308.15 and 313.15 K. All the excess molar volumes of mixing are negative or very close to zero. Generally, the absolute values of the excess molar volume of mixing increase with an increase in the difference between the number of carbon atoms of the components constituting the system.

Excess and partial excess molar volumes of mixing trimethyl- and triethylphosphate with water

Excess and excess partial molar volumes of mixing of the systems trimethylphosphate (TMP) and triethylphosphate (TEP) with water were determined at 15, 20, 25, 30 and 35°C. Negative deviation from ideal behavior were observed for the two systems studied, with a minimum at x TMP =0.40 and x TEP =0.35. Excess volume values in general decrease with temperature, and are smaller for the TMP-water system.

The Behavior of Mixing in Liquid Binary Alloys. Volume of Mixing in the Systems Lead–Tin, Lead–Antimony, and Lead–Thallium

Abstract The molar volume of mixing in the liquid systems Pb–Sn, Pb–Sb, and Pb–Tl has been studied by means of silica glass pycnometer at 1045, 907, and 773 K respectively. The volumes of mixing in the systems Pb–Sn and Pb–Tl are slight positive (0.0263×10−6–0.1767×10−6 m3mol−1), while that in the system Pb–Sb is slight negative (−0.1524×10−6 m3mol−1).

Excess and partial excess molar volumes of mixing of N,N-dibutyl-2-ethylhexamide with dodecanol

Excess and excess partial molar volumes of mixing of the system N,N-dibutyl-2-ethylhexylamide (DBEHA) + dodecanol (DDA) were determined at 25, 35, 45, 55 and 65°C. The excess molar volumes exhibit a maxima at each temperature at approximatelyxDBEHA = 0.3 and a minima close toxDBEHA = 0.9. The values of the excess volumes in general increase with the temperature. The partial excess molar volumes are calculated from the smoothed data and the results are discussed in the light of postulated amide-alcohol interactions.

Volume and compressibility changes in aqueous mixed-salt solutions at 25 °C

The excess molar volumes of mixing (ΔmVex) and compression of mixing [Δm(βV)ex] have been calculated from the measured density and sound velocity parameters for aqueous binary and ternary solutions of NaCl–KCl, LiBr–KBr, RbBr–KBr, CsBr–KBr, Me4NBr–KBr, Et4NBr–Me4NBr and Bu4NBr–Me4NBr at 25 °C (in the concentration range 0.1–1.0 mol kg–1 and at constant ionic strength of I≈ 0.2, 0.5 and 1.0 mol kg–1 in ternary solutions). ΔmVex and Δm(βV)ex exhibit parabolic behaviour as a function of y[the fraction of ionic strength due to an electrolyte (AX) in a mixture of two electrolytes (AX + BX)]. Application of the Friedman equation to the ΔmVex and Δm(βV)ex values indicated the presence of cation–cation interactions and specificity of the cosphere overlapping effects, which in turn depend upon the nature of the ion pairs, the water structural effects and hydrophobic interactions in solutions. The results are discussed in terms of the combination of water structure-breaking and structure-making properties of ions. The compressional results show that in alkali-metal halide mixtures, electrostatic interactions affect more water molecules in mutual volumes derived from the ionic cosphere overlapping or interact over greater distances than tetra-alkylammonium salts.

X-ray study of phases and structures in 3He-4He solid solutions.

X-ray diffraction has been used to study structural and thermodynamic aspects of isotopic phase separation in solid mixtures of $^{3}\mathrm{He}$ and $^{4}\mathrm{He}$. The phase-separation process has been followed in crystals of 51%, 28%, and 12% $^{3}\mathrm{He}$ and melting pressures between 3.0 and 6.1 MPa. The phase-separation temperatures determined in this work on massive crystals are in general agreement with previous work using other techniques. The pressure dependence of ${T}_{c}$, the highest temperature on the coexistence curve, is found to be linear: ${\mathrm{dT}}_{c}$/dP=-34 mdeg/MPa. The resulting molar volume of mixing is ${v}^{E}$=-0.54x(1-x) ${\mathrm{cm}}^{3}$. Deviation from regular solution behavior, reported in the literature, while possible, is not confirmed. The results of these x-ray measurements also yield detailed structural information which modifies previous understanding of the low-temperature, low-pressure phase diagram of helium isotopic mixtures.

Volume and compressibility changes in mixed-salt solutions at 25 °C

The excess molar volumes of mixing (ΔmVex) and compression of mixing [Δm(βV)ex] have been calculated from the measured density and sound-velocity data for aqueous binary and ternary solutions involving NaBr–KBr, Bu4NBr–KBr and Bu4NBr–Et4NBr as solutes at 25 °C (in the concentration range 0.05–1.0 mol kg–1 and at constant ionic strength of I≈ 0.2, 0.5 and 1.0 in ternary solutions. The ΔmVex and Δm(βV)ex values exhibit parabolic behaviour as a function of y[the fraction of ionic strength due to an electrolyte (AX) in a mixture of two electrolytes (AX + BX)]. On application of Friedman equation the ΔmVex values show the presence of large cation–cation interactions in the solutions involving n-tetrabutylammonium bromide. The excess compression values of solutions and their variation with ionic strength indicate the effect of ion–ion interactions on the co-sphere water in a subtle way.

Solid State Chemical Model for the Solubility Behaviour of Homogeneous Solid Co‐Mn‐Carbonate Mixtures

AbstractA continuous series of homogeneous solid mixtures Co(1‐x)MnxCO3 was synthesized by an autoclave method. In agreement with the formalism of ideal and regular solid ionic mixtures, the excess molar volume of mixing was negligible and the cation‐anion distances obeyed Vegard's rule in the whole compositional range. Solubility measurements using the pH variation method revealed that Co(1‐x)MnxCO3 phases dissolved congruently in aqueous acidic media at 50°C. Thermodynamic analysis of the solubility data showed that a closer fit was obtained assuming regular rather than ideal mixing.

Infrared spectra of the vitreous system Co3O4-P2O5 and their interpretation

The infrared absorption spectra of the vitreous Co3O4-P2O5 system have been measured in the frequency region 4000 to 200 cm−1. Absorption bands and mode attributions have been fully discussed. Absorption frequencies and intensities are found to be strongly and systematically dependent on glass composition. On this basis it is found that this glass system can be divided into three distinct “compositional regions”. Similar “three region” behaviour is reported for the compositional dependence of density and molar volume of mixing of Co3O4-P2O5 glass. Quantitative justification for the band attributions has been attempted.

Pressure Effect on the Concentration Fluctuations for Liquid Na-Ga and Na-Cd Mixtures with S-Shape Liquidus Curves

Abstract Measurements of the electromotive force (EMF) for liquid Na-Ga and Na-Cd mixtures have been made up to 630°C and 700 bar by using β-alumina as a separator. The pressure variations of thermodynamic quantities, such as free energy, enthalpy and entropy, etc., are obtained. The concentration variation of the molar volume of mixing is deduced from the relative partial molar volume determined directly from the pressure derivative of the EMF. The concentration fluctuations for both mixtures are large in the Na-rich concentration range and diminish considerably by a slight application of pressure. The difference of the pressure effect on the concentration fluctuations between the liquid Na-Ga and Na-Cd mixtures is discussed.

« Average atomic order effects » in liquid binary alloys

The « average atomic order effects » is defined in liquid alloys by means of a Δx function giving the deviation from the average composition. On the basis of statistical mechanics and fluctuation theory, Δx is related to the chemical potential and the partial molar volumes of mixing. Two order parameters, a chemical order parameter and a volume order parameter, are considered. This approach is applied to the systems Fe — C and Bi — Zn.