Values Of Molar Volume Research Articles

Study of thermodynamic properties of aqueous binary mixtures of glycine, l-alanine and β-alanine at low temperatures ( T = 275.15, 279.15, and 283.15) K

In the present communication, experimental values of density ( ρ) and speed of sound ( u) of aqueous solutions of three amino acids, namely glycine, l-alanine and β-alanine at different temperatures i.e. T = (275.15, 279.15, and 283.15) K are reported. From the experimental values, different derived parameters such as apparent molar volume of solute ( ϕ V ), isentropic compressibility of solution ( β S), apparent molar isentropic compressibility of solute ( ϕ KS ) have been calculated. The limiting values of apparent molar volume of solute ( ϕ V 0 ) , apparent molar isentropic compressibility of solute ( ϕ KS 0 ) and apparent molar expansivity ( ϕ E 0 ) in the aqueous medium have also been obtained. The temperature coefficients of these limiting properties have also been computed. The results obtained were interpreted in terms of solute–solvent and solute–solute interactions, and structure making and structure breaking abilities of the solute in aqueous medium.

Effect of the temperature on the physical properties of pure 1-propyl 3-methylimidazolium bis(trifluoromethylsulfonyl)imide and characterization of its binary mixtures with alcohols

In this paper, physical properties of a high purity sample of the ionic liquid 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [PMim][NTf 2], and its binary mixtures with methanol, ethanol, 1-propanol, and 2-propanol were measured at atmospheric pressure. The temperature dependence of density, refractive index and speed of sound (293.15 to 343.15) K and dynamic viscosity (298.15 to 343.15) K were studied at atmospheric pressure by conventional techniques for the pure ionic liquid. For its mixtures with alcohols, density, speed of sound, and refractive index were measured at T = 298.15 K over the whole composition range. The thermal expansion coefficient of the [PMim][NTf 2] was calculated from the experimental results using an empirical equation, and values of the excess molar volume, excess refractive index, and excess molar isentropic compressibility for the binary systems at the above mentioned temperature, were calculated and fitted to the Redlich–Kister equation. The heat capacity of the pure ionic liquid at T = 298.15 K was determined using DSC.

Apparent molar volume and apparent molar adiabatic compressibility of 2-hydroxy-5-methyl acetophenone in N,N-dimethylformamide at different temperatures

The speed of sound and density of 2-hydroxy-5-methyl acetophenone in dimethylformamide have been measured over the range of temperatures 25–40 °C. From the experimentally determined data, values of apparent molar volume (V ϕ), adiabatic compressibility (βs), apparent molar adiabatic compressibility (K s,ϕ) and their limiting values have been computed. Values at infinite dilution provide information regarding solute–solvent interaction. The density and velocity increases with increase in concentration and decreases with increase in temperature. These results have been analyzed in terms of molecular interactions between acetophenone and dimethylformamide.

Glass formation area and characterization studies in the CdO–WO 3–TeO 2 ternary system

The glass formation area in the CdO–WO 3–TeO 2 ternary system was determined and thermal and structural features of the ternary glasses were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Raman scattering methods and the variation of the glass properties and structural transformations were discussed in terms of the glass composition comparing with the literature. For all ternary glass samples, the glass transition ( T g) and crystallization ( T c/ T p) temperatures, glass stability (Δ T), activation enthalpy for glass transition (Δ H * ) and fragility parameter ( m) values were calculated from the DSC thermograms. Density ( ρ), molar volume ( V M ) and oxygen molar volume ( V O ) values and the refractive indices ( n) at a wavelength of 632 nm were measured. Raman spectra of the glasses were interpreted in terms of the structural transformations on the glass network resulted by the changing WO 3 + CdO/TeO 2 ratio.

Apparent molar volumes and transport behavior of glycine and l-valine in aqueous solutions of tripotassium citrate at T = (308.15 and 318.15) K

Densities and viscosities of glycine and l-valine have been measured at 308.15 and 318.15 K in aqueous tripotassium citrate solutions ranging from 0.2 to 0.8 mol kg − 1 of tripotassium citrate. The viscosity data have been analyzed by Jones–Dole equation. The activation parameters of viscous flow have been obtained to throw light on the mechanism of viscous flow. The values of apparent molar volume, partial molar volume at infinite dilution and relative viscosities of each amino acid in various aqueous tripotassium citrate solutions have been evaluated from the density and viscosity data. The partial molar volumes of transfer from water to aqueous tripotassium citrate solution at infinite dilution have also been calculated. Transfer volume data have been used to calculate the pair and triplet interactions. The results have been discussed in terms of solute–solute and solute–solvent interactions and the structural changes of the solutes in solutions.

Thermodynamic properties of binary liquid mixtures of diethylenetriamine with alcohols at different temperatures

Densities, ρ, viscosities, η, and speeds of sound, u, were measured for the binary liquid mixtures containing diethylenetriamine with 2-methyl-1-propanol, 2-propanol and 1-butanol at 293.15, 298.15, 303.15, 308.15 and 313.15 K. From density and speed of sound data, excess molar volumes, V m E and deviations in isentropic compressibility, Δ κ s , and speed of sound, Δ u have been evaluated. Viscosity data were used to compute deviations in viscosity and excess Gibbs energy of activation of viscous flow Δ G* E at 298.15, 303.15 and 308.15 K. A Redlich–Kister type equation was applied to fit the excess molar volumes and deviations in isentropic compressibility, speed of sound and viscosity data. The viscosity data have been correlated with the equations of Grunberg–Nissan, Tamura–Kurata, Heric–Brewer and of Hind et al. All the binary systems of the present study have negative values of excess molar volumes and deviations in isentropic compressibility over whole composition range and at all temperatures which indicates strong interactions between the components of binary mixtures.

Thermodynamics of the interactions of a homologous series of some amino acids with trimethylamine N-oxide: Volumetric, compressibility, and calorimetric studies

The values of apparent molar volume V 2 ,ϕ and apparent molar compressibility K S, 2 ,ϕ of glycine, l-alanine, dl-α-amino-n-butyric acid, l-valine, and l-leucine have been determined in the aqueous solution of 1 mol · kg −1 and 2 mol · kg −1 trimethylamine N-oxide (TMAO) solutions by density and sound velocity measurements. Isothermal titration calorimetry has been employed to determine the values of heats of dilution q of the aqueous solutions of these amino acids in TMAO at temperatures from T = 288.15 K to T = 308.15 K. These data have been used to calculate values of the infinite dilution standard partial molar volume ( V 2 , m ∘ ), standard partial molar isentropic compressibility ( K S , 2 , m ∘ ) and limiting enthalpy of dilution (Δ dilH °) of the amino acids in aqueous TMAO solutions. The standard partial molar volumes of transfer ( Δ tr V 2 , m ∘ ), isentropic compressibility of transfer ( Δ tr K S , 2 , m ∘ ), and enthalpy of dilution of transfer (Δ tr Δ dilH °) of amino acids from water to aqueous TMAO solutions have been calculated from the measured quantities for these thermodynamic quantities. The linear correlation of V 2 , m ∘ for a homologous series of amino acids has been utilized to calculate the contribution of the charged end groups ( NH 3 + , COO −), CH 2 groups, and the other alkyl chains of the amino acids to V 2 , m ∘ . The results for the partial molar properties of transfer from water to aqueous TMAO solutions have been interpreted in terms of ion–ion, ion–polar, hydrophilic–hydrophobic, and hydrophobic–hydrophobic group interactions. The volume, compressibility, and enthalpy of dilution of transfer data suggest that hydrophobic interactions predominant in this system. It is inferred that the effect of TMAO on protein stability need not be necessarily due to preferential hydration, it can also interact with the hydrophobic groups of the constituents of protein affecting its stability.

Densities, Viscosities, Speeds of Sound, and Refractive Indices of Binary Mixtures of 1-Decanol with Isomeric Chlorotoluenes

Densities, ρ, viscosities, η, speeds of sound, u, and refractive indices, n D, of binary liquid mixtures of 1-decanol with o-chlorotoluene, m-chlorotoluene, and p-chlorotoluene have been measured over the entire range of composition at 298.15 K, 303.15 K, and 308.15 K and at atmospheric pressure. From the experimental data of density, speed of sound, viscosity and refractive index, the values of the excess molar volume, V E, deviations in isentropic compressibility, Δκ S , and deviations in molar refraction, ΔR, have been calculated. The calculated excess and deviation functions have been analyzed in terms of molecular interactions and structural effects.

Studies on Molecular Interactions of Some Electrolytes in Water by Volumetric and Viscometric Measurments at <i>T</i>= (303.15 to 323.15 K)

The viscosities and densities of potassium chloride, potassium nitrate, magnesium chloride, and magnesium nitrate have been measured at 303.15, 308.15, 313.15, 318.15 and 323.15 K in aqueous solution. The viscosity data were analyzed by using Jones–Dole equation. The values of apparent molar volume, limiting apparent molar volume have been evaluated from the density data. The results were interpreted in the light of ion–ion and ion–solvent interactions and of structural effects of the solutes in solution.Keywords: Density; Apparent molar volume; Viscosity; Jones–Dole equation.© 2011 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi:10.3329/jsr.v2i2.6288 J. Sci. Res. 3 (2), 437-444 (2011)

Partial Molar Volumes and Partial Molar Isentropic Compressions of γ-Butyrolactone and ε-Caprolactone at Infinite Dilution in Water at Temperatures (278.15 to 318.15) K and at Atmospheric Pressure

Density and speed-of-sound values at T = (278.15, 283.15, 288.15, 293.15, 298.15, 308.15, and 318.15) K and at atmospheric pressure were measured, for dilute aqueous solutions of γ-butyrolactone and e-caprolactone, using an Anton Paar DSA 5000 vibrating-tube densimeter and sound analyzer. A small but significant effect of hydrolysis was observed for aqueous e-caprolactone and a procedure for eliminating its effect was proposed and employed. Values of the partial molar volume and isentropic compression at infinite dilution were obtained from this experimental data by suitable extrapolation procedures and compared with available data from the literature. The group contribution of the methylene group was evaluated and compared with that obtained for other classes of aqueous cyclic solutes.

Parameters of viscous flow in dilute solutions of polyalkyl glycol ethers in secondary alcohols

Densities and viscosities were measured for the binary dilute mixtures of triethylene glycol monomethyl ether (TRIEGMME) in 2-alcohols (2-propanol (2-PR), 2-butanol (2-BU), and 2-pentanol (2-PE)) and tetraethylene glycol dimethyl ether (TEGDME) in 2-pentanol, at temperatures from 288.15 K to 318.15 K and in 0 ≤ x 2 ≤ 0.10 mol fraction range of the polyalkyl glycol ethers. The values of the dynamic viscosity in the TRIEGMME + 2-PR systems are more viscous than pure solvent at the work temperatures. The Jones–Dole B coefficients and β G interaction parameters for viscous flow values were calculated and explain the behavior observed. The partial molar volumes at infinite dilution of solute in 2-alkanols were calculated by the parameters of viscous flow obtained in dilute solutions polyalkyl glycol ethers in 2-alkanols. The values have been compared with the values of partial molar volume at infinite dilution obtained by density measurement for both solutes in the 2-propanol, 2-butanol, and 2-pentanol.

Enthalpy of dilution and volumetric properties of N-glycylglycine in aqueous xylitol solutions at T = 298.15 K

The enthalpy of dilution of N-glycylglycine (Δ dil H m) in aqueous xylitol solutions has been determined by means of flow-mix isothermal microcalorimetry at the temperature of 298.15 K. The homogeneous enthalpic interaction coefficients ( h 2, h 3, and h 4) which characterize the interactions of examined N-glycylglycine in aqueous xylitol solutions have been calculated according to the excess enthalpy concept based on the values of dilution enthalpy. It has been found that the enthalpic pair interaction coefficients ( h 2) in the systems investigated are negative and become less negative as the molality of xylitol increases. Values of the density ( ρ) of the ternary homogeneous systems were also measured with a quartz vibrating-tube densimeter at the temperature of 298.15 K. The values of the apparent molar volume ( V ϕ ) of the ternary systems were calculated from the data of density, which have been used to deduce limiting partial molar volumes of N-glycylglycine ( V ϕ o ) and limiting partial molar volumes of transfer ( Δ trs V ϕ o ) from water to aqueous xylitol solutions at different concentrations. The results have been discussed based on solute–solute interactions and solvation effects.

Thermodynamics of dilute aqueous solutions of imidazolium based ionic liquids

Experimental measurements of density ρ, speed of sound u, and viscosity η of aqueous solutions of various 1-alkyl-3-methylimidazolium based ionic liquid (IL) solutions have been performed in dilute concentration regime at 298.15 K to get insight into hydration behaviour of ILs. The investigated ILs are based on 1-alkyl-3-methylimidazolium cation, [C n mim] having [ BF 4 ] - , [Cl] −, [ C 1 OSO 3 ] - , and [ C 8 OSO 3 ] - as anions where n = 4 or 8. Several thermodynamic parameters like apparent molar volume φ V , isentropic compressibility β s , and viscosity B-coefficients have been derived from experimental data. Limiting value of apparent molar volume has been discussed in terms of intrinsic molar volume ( V int ) molar electrostriction volume ( V elec ), molar disordered ( V dis ), and cage volume ( V cage ). Viscosity B-coefficients have been used to quantify the kosmotropic or chaotropic nature of ILs. Hydration number of ILs obtained using elctrostriction volume, isentropic compressibility, viscosity, and differential scanning calorimetry have been found to be comparative within the experimental error. The hydrophobic hydration has found to play an important role in hydration of ILs as compared to hydration due to hydrogen bonding and electrostriction. Limiting molar properties, hydration numbers, and B-coefficients have been discussed in terms of alkyl chain length of cation or nature of anion.

A critical assessment of capillary condensation and evaporation equations: A computer simulation study

Grand Canonical Monte Carlo simulation (GCMC) is used to study the capillary condensation and evaporation of argon adsorption in finite-length carbon cylindrical nanopores. From the simulation results of local density distributions in the radial and axial directions we obtain the contact angle and the core radii just before condensation and just after evaporation. These are then used in the Kelvin equation (evaporation) and Cohan equation (condensation) to obtain the product of surface tension and liquid molar volume. This product is found to be always greater than for the bulk liquid. We test this deviation with pores of different length and radius and find that both affect the derived product of surface tension and liquid molar volume. The implication of this finding is that if the values of surface tension and liquid molar volume of the bulk phase are used in the Kelvin equation the pore radius will be underestimated. For argon adsorption in cylindrical pores we propose that the Kelvin and Cohan equations should be modified to take account of the difference between the fluid in the adsorbed phase in the confined space and that in the bulk phase.

Density and molar volume studies of phosphate glasses

The density and molar volume of some phosphate glasses (xNa2O?(100-x)P2O5, x = 30, 35, 40, 45, 50); xB2O3?(1-x)NaPO3, x = 5, 10, 15, 20, 25; xNa2O?(30-x) K2O?10Al2O3? 25B2O3?35P2O5, x= 5, 10, 15, 20, 25) glasses were determined, in order to study their structure. The density of the glasses increased while their molar volume values decreases with the increase of sodium oxide content in phosphate glasses. The results obtained could be correlated to several factors such as the polarization, the field strengths and the ionic radii of the different incorporated cations.

Volumetric Properties of Some Aliphatic Mono- and Dicarboxylic Acids in Water at 298.15 K

The apparent molar volumes, Vφ, of two series of homologous aliphatic carboxylic acids, H(CH2)nCOOH [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 \(V_{\phi (u)}^{0}\) were also calculated. The variation of \(V_{\phi (u)}^{0}\) was determined as a function of the aliphatic chain length of the studied carboxylic acids.

Density, Viscosity, and Speed of Sound of (1-Octanol + 2-Methoxyethanol), (1-Octanol + N,N-Dimethylacetamide), and (1-Octanol + Acetophenone) at Temperatures of (298.15, 308.15, and 318.15) K

Densities and viscosities of the binary mixtures of 1-octanol + 2-methoxyethanol (2ME), + N,N-dimethylacetamide (DMAc), and + acetophenone (APH) were measured over the entire range of composition at T = (298.15, 308.15, and 318.15) K. Ultrasonic speeds of these binary mixtures have also been measured at 298.15 K. From the experimental data, values of excess molar volumes (VE), viscosity deviations (Δη), and excess isentropic compressibility (κSE) have been calculated. These results were fitted to the Redlich−Kister polynomial equation. Partial molar volumes of 2ME/DMAc/APH in 1-octanol at infinite dilution and at different temperatures have also been evaluated. The results were discussed in terms of molecular interactions prevailing in the mixtures. The measured viscosities were correlated with McAllister’s three-body interaction model.

Vapor−Liquid Equilibria, Density, and Speed of Sound of Aqueous Solutions of Sodium Dihydrogen Citrate or Disodium Hydrogen Citrate

Vapor−liquid equilibrium data (water activity, vapor pressure, osmotic coefficient, and activity coefficient) of binary aqueous sodium dihydrogen citrate or disodium hydrogen citrate solutions were obtained through the isopiestic method at T = 298.15 K. Density and speed of sound measurements were carried out on the aqueous solutions of the mentioned electrolytes at T = (288.15 to 308.15) K at atmospheric pressure. From the experimental density and speed of sound data, the apparent molar volume and isentropic compressibility values were evaluated and fitted to the Pitzer equation from which the apparent molar volume and apparent molar isentropic compressibility of the solutions at infinite dilution were calculated at each temperature within the above-mentioned range.

Refractive Index of Liquid Mixtures: Theory and Experiment

An innovative approach is presented to interpret the refractive index of binary liquid mixtures. The concept of refractive index "before mixing" is introduced and shown to be given by the volume-fraction mixing rule of the pure-component refractive indices (Arago-Biot formula). The refractive index of thermodynamically ideal liquid mixtures is demonstrated to be given by the volume-fraction mixing rule of the pure-component squared refractive indices (Newton formula). This theoretical formulation entails a positive change of refractive index upon ideal mixing, which is interpreted in terms of dissimilar London dispersion forces centred in the dissimilar molecules making up the mixture. For real liquid mixtures, the refractive index of mixing and the excess refractive index are introduced in a thermodynamic manner. Examples of mixtures are cited for which excess refractive indices and excess molar volumes show all of the four possible sign combinations, a fact that jeopardises the finding of a general equation linking these two excess properties. Refractive indices of 69 mixtures of water with the amphiphile (R,S)-1-propoxypropan-2-ol are reported at five temperatures in the range 283-303 K. The ideal and real refractive properties of this binary system are discussed. Pear-shaped plots of excess refractive indices against excess molar volumes show that extreme positive values of excess refractive index occur at a substantially lower mole fraction of the amphiphile than extreme negative values of excess molar volume. Analysis of these plots provides insights into the mixing schemes that occur in different composition segments. A nearly linear variation is found when Balankina's ratios between excess and ideal values of refractive indices are plotted against ratios between excess and ideal values of molar volumes. It is concluded that, when coupled with volumetric properties, the new thermodynamic functions defined for the analysis of refractive indices of liquid mixtures give important complementary information on the mixing process over the whole composition range.

Solvent effect on the heat of solution and partial molar volume of magnesium perchlorate

AbstractFor magnesium perchlorate (MP), the solvent effect on the heat of solution and partial molar volumes (PMV) at 25 °C was studied. Since the complete dissociation of magnesium perchlorate is more difficult to achieve as compared with lithium perchlorate (LP), the concentration dependence of the values of the heat of solution and partial molar volume were noted. Only in highly polar solvents with large donor numbers (DN), such as water, dimethyl sulfoxide, N,N‐dimethyl formamide, and formamide, the differential and integral values of the enthalpies of solution were the same in the range of concentrations studied. In all solvents studied, the values of the heat of solution of MP were highly exothermic and exceed that of LP by more than 30 kcal mol−1. The values of the partial molar volume of MP were changed from 82.3 cm3 mol−1 in formamide to −2.4 cm3 mol−1 in acetone, and correlate linearly with that of LP (R = 0.975). Taking into account the significant change in the properties of molecules in the solvate shell of cation Mg2+, the large increase in the reactivity of reactants, activated by such interaction with Mg2+ cation is expected. Copyright © 2010 John Wiley & Sons, Ltd.