Thermodynamic Properties Of Liquid Mixtures Research Articles

Effects of intramolecular chain conformation on the hydration and miscibility of polyethylene glycol in water studied by means of polymer reference interaction site model theory.

To examine the conventional idea that the gauche conformation of the OCCO dihedral angle promotes the dissolution of polyethylene glycol (PEG) in water through strong hydration, the thermodynamic properties of liquid mixtures of PEG and water were studied by means of polymer reference interaction site model (PRISM) theory. The intramolecular correlation functions required as input for PRISM theory were calculated by the generator matrix method, accompanied by changes in the distribution of dihedral angles. In the infinite dilution limit, the increased probability of gauche conformation of the OCCO dihedral angles stabilizes the hydration of PEG through enhanced hydrogen bonding between the ether oxygen of PEG and water. The mixing Gibbs energies of the liquid mixtures were also calculated in the whole concentration range based on the Gibbs-Duhem equation, as per our recent proposal. A liquid-liquid phase separation was observed when all the dihedral angles of PEG were in the trans conformation; for the liquid mixture to be miscible in the whole concentration range, the introduction of the OCCO gauche conformation was found to be indispensable. The above theoretical results support the conventional idea that the OCCO gauche conformation is important for the high miscibility of PEG and water.

Critical review on graph theory: Estimation of thermodynamic properties of liquid mixtures

Critical review on graph theory: Estimation of thermodynamic properties of liquid mixtures

Study of phase equilibria and thermodynamic properties of liquid mixtures using the integral equation theory: Application to water and alcohol mixtures.

A theoretical method for calculating the thermodynamic properties and phase equilibria of liquid-liquid mixtures using the integral equation theory is proposed. The solvation chemical potentials of the two components are evaluated by the integral equation theory and the isothermal-isobaric variation of the total density with composition is determined to satisfy the Gibbs-Duhem relation. Given the density of a pure component, the method can calculate the densities of the mixture at any composition. Furthermore, it can treat the phase equilibrium without thermodynamic inconsistency with respect to the Gibbs-Duhem relation. This method was combined with the reference interaction-site model integral equation theory and applied to mixtures of water + 1-alcohol by changing the alcohol from methanol to 1-butanol. The destabilization of the mixing Gibbs energy by increasing the hydrophobicity of the alcohol and demixing of the water-butanol mixture were reproduced. However, quantitative agreement with experiments is not satisfactory, and further improvements of the integral equation theory and the molecular models are required.

Thermodynamic Properties of Binary Liquid Mixtures Containing Furfural with Chlorobenzene, Nitromethane, Diethylmalonate and 1-Butanol at 308.15K and 318.15K Supported by FTIR Spectral Studies

A study on thermodynamic properties of the liquid mixture is used in the industrial process, which often extends to solution chemistry. Density(ρ), Viscosity(η), and Ultrasonic velocity(U) were determined for binary liquid mixtures of furfural with chlorobenzene, nitromethane, diethyl malonate and 1- butanol at temperature of 308.15K and 318.15K at atmospheric pressure over the whole range of mole fractions. The calculated thermodynamic properties and some excess parameters such as Excess Volume(VE), Deviation in Isentropic Compressibility(∆KS), Deviation in Viscosity(∆η), Deviation in Intermolecular Free Length(∆LF), Deviation in Intermolecular Free Volume(∆VF), Deviation in Internal Pressure(∆π) and Deviation in Acoustic Impedance(∆Z) were calculated and applied to the Redlich-Kister type polynomial equation to determine the appropriate coefficients. The effects of composition and temperature on thermodynamic parameters have been studied in terms of molecule interaction in these liquid mixtures. Further, IR spectra of these liquid mixtures were recorded and the data were utilized to examine the mixing behavior of the components.

Study of solvation and pollution approch of atrazine and chlorothalonil pesticides in binary liquid mixtures

Thermodynamic properties of liquid mixtures are communally used to examine the deviation from ideality. The thermodynamic properties, which depend on temperature, composition and pressure, describe interaction between the component molecules. The solubility is a property of solute and solvent that effect on extent of adsorption–desorption of pesticides. Hence solution chemistry utilized for investigation of environmental fate of agrochemicals and pollutants in the environment. Some pesticides can leach through the soil and enter into the groundwater. In India about 60 % of the population depends upon ground water for drinking purpose and almost 95 % of the households in rural areas use ground water as their primary source of drinking water. Drinking water supplies might be contaminated by pesticides. The excess use of pesticides leads to environmental contamination and the pesticide residues are found in food, water and air. This paper addresses a study of solvation behavior of Atrazine and Chlorothalonil pesticides in binary mixture of DMF and DMSO. The measured densities (ρ) and viscosities (η) at 298.15 to 313.15 K using a bicapillary pycnometer and Ubbelohde viscometer were utilize to study salvation and pollution approach of pesticides. The obtained parameters were interpreted in terms of solute–solute and solute–solvent interactions. The proposed method for study of solvation behavior of pesticides by viscometer is simple, robust and requires less computational time. Each pesticide and solvent molecules are nanoparticles. Recommendation from this research work could help to change physiochemical behavior of pesticides used in agriculture field to becomes more eco-friendly for the sustainable development in environment.

Thermodynamic properties of liquid mixtures containing cyclic amines and isomeric picolines: excess molar volumes and excess isentropic compressibilities and excess heat capacities

The present study reports densities, ρ, speeds of sound, u, molar heat capacities, CP of binary piperidine or 1-methylpiperidine (1) + 2- or 3- or 4-picolines (2) mixtures over entire composition range by varying temperature range from 293.15 to 308.15 K with step of 5 K interval. Experimental data have been used to access excess molar volumes, VE, excess isentropic compressibilities, $$\kappa_{{\rm S}}^{\text{E}}$$ and excess heat capacities, $$C_{{\rm P}}^{\text{E}}$$ . The VE, $$\kappa_{{\rm S}}^{\text{E}}$$ and $$C_{{\rm P}}^{\text{E}}$$ data have been fitted to Redlich–Kister polynomial equation to evaluate the adjustable parameters and standard deviations. The $$C_{{\rm P}}^{\text{E}}$$ data of piperidine (1) + 2- or 3- or 4-picolines (2); 1-methylpiperidine (1) + 3- or 4-picolines (2) are positive and those for 1-methylpiperidine (1) + 2-picoline (2) mixture, sign and magnitude of $$C_{{\rm P}}^{\text{E}}$$ values change with increase in mole fraction of 1-methylpiperidine. Further, VE and $$\kappa_{{\rm S}}^{\text{E}}$$ of 1-methylpiperidine (1) + 2- or 3- or 4-picolines (2); piperidine (1) + 2- or 3-picolines (2) are negative; and those for piperidine (1) + 4-picoline (2) are positive across full range of composition. The VE, $$\kappa_{{\rm S}}^{\text{E}}$$ and $$C_{{\rm P}}^{\text{E}}$$ data have been utilized to test the applicability of Graph theory. It has been observed that VE, $$\kappa_{{\rm S}}^{\text{E}}$$ and $$C_{{\rm P}}^{\text{E}}$$ values calculated from the Graph theory compare reasonably well with their corresponding experimental values. The Quantum mechanical calculations and IR spectral studies on the aforesaid mixtures support the presence of various molecular entities (estimated by analyses of VE data) in pure and mixed state.

Experimental Results of the Dynamic Characteristics of Methanol- and Ethanol-Water Mixtures at Temperature Range of 35 - 70oc Using an Innovative Technique by Physical Method

The analysis of some thermodynamic properties of liquid mixtures was reported. The properties of methanol-water mixture, ethanol-water mixtures such as; density, viscosity, activation energy, enthalpy and entropy were evaluated. These parameters were investigated at different temperatures and constant atmospheric pressure using an innovative technique designed and constructed for the purpose of analysis of water-mixtures in solutions. The activation energy of water, methanol, ethanol, methanol-water mixture and ethanol-water mixture were 14.49±0.17, 9.05±0.11, 14.92±0.21, 12.17±0.21 and 14.73±0.09 kJ.mol −1 respectively. The corresponding enthalpy and entropy of the liquids were also calculated from the experimentally determined parameters.

Exact Local Composition Model for Two-Dimensional Lattice Fluids

The knowledge on the deviation of local composition from bulk composition has been proven to be powerful for modeling the excess thermodynamic properties of liquid mixtures. However, the exact solution to the local compositions is available for a few cases, such as the one-dimensional (1D) lattice fluids and for certain two-dimensional (2D) lattice fluids (the Ising models). We discover that the long-range correlation in the fluid structure, which is not present in 1D but is important in 2D, is the main reason for the complication of getting the exact local compositions for general 2D lattice fluids. In this work, a general approach for calculating the local compositions in 2D lattice fluids is developed. We show that for any stripe-like 2D lattices, the long-range correlations can be avoided by transforming the system to a multicomponent 1D system. The local compositions of such a system can be determined by minimization of the free energy of the mixture. We found that the local compositions, energy, and...

Study of Acoustical and Thermodynamical Properties of Aqueous Ammonium Dihydrogen Orthophosphate

Ultrasonic is an effective tool for studying the nature and strength of molecular interactions of binary mixtures. In this present work, molecular interactions of Ammonium dihydrogen orthophosphate (ADP)electrolyte were studied using Ultrasonic method. The sound velocity is one of those physical properties that helps in understanding the nature of liquid state. Ultrasound velocity, density and viscosity of ammonium dihydrogen orthophosphate electrolyte were measured at 303 K, 308 K, 313 K,318 K and 323 K. The data obtained during the study is used for determining the various acoustical parameters like acoustic impedance, adiabatic compressibility, Rao’s constant, Wada’s constant, molar and molal salvation number, molar and molal volume, molar and molal solvated volume. Thermodynamical parameters such as internal pressure, free volume and relaxation time are also calculated. Thermodynamic properties of liquid mixtures have been extensively used to study the departure of a real liquid mixture behavior from ideality. The ultrasonic study of liquids is of immense important in understanding the biological activity of drug molecules and the activation energy of the metabolic process basically depend on the type and strength of the intermolecular interactions. Ammonium dihydrogen phosphate (ADP), also known asmono ammonium phosphate (MAP),NH4H2PO4 is often used in the blending of dry agriculturalfertilizers, fire retardant for wood, paper, fabric, dispersant for fiber processing and dyeing industry, glaze for enamel, cooperating agent for fire retardant coating, decontamination agent for match stalk and candle core.

Orientational effects in alkanone, alkanal or dialkyl carbonate + alkane mixtures and in alkanone + alkanone or + dialkyl carbonate systems

Interactions and structure of alkanone, or alkanal or dialkyl carbonate+alkane mixtures, or of 2-alkanone+2-alkanone, or of ketone+dialkyl carbonate systems have been investigated by means of a set of thermodynamic properties and by the application of the Flory model. The properties considered are excess molar quantities: enthalpies, HmE, volumes, VmE, or isobaric heat capacities, CpmE, and liquid-liquid equilibria. Experimental data show that alkane mixtures are characterized by rather strong dipolar interactions. In the case of systems containing ketones with the same number of C atoms and a given alkane, dipolar interactions become weaker in the sequence: aromatic>cyclic>linear. In addition, the mentioned interactions become also weaker in the order: dialkyl carbonate>linear alkanone>linear alkanal. This is an important result, as carbonates show lower effective dipole moments than the other compounds, and it suggests that the group size may be relevant when evaluating thermodynamic properties of liquid mixtures. Results on HmE from the Flory model show that orientational effects (i.e., non-random mixing) are rather similar for systems with linear, cyclic or aromatic ketones or alkanals and alkanes. In contrast, orientational effects become weaker in dialkyl carbonate+alkane mixtures. The behavior of 2-alkanone +2-alkanone systems and of mixtures of longer 2-alkanones or cyclohexanone with dialkyl carbonate is close to random mixing. Larger orientational effects are encountered in solutions of carbonates and shorter 2-alkanones.

Accurate schemes for calculation of thermodynamic properties of liquid mixtures from molecular dynamics simulations.

We explore different schemes for improved accuracy of entropy calculations in aqueous liquid mixtures from molecular dynamics (MD) simulations. We build upon the two-phase thermodynamic (2PT) model of Lin et al. [J. Chem. Phys. 119, 11792 (2003)] and explore new ways to obtain the partition between the gas-like and solid-like parts of the density of states, as well as the effect of the chosen ideal "combinatorial" entropy of mixing, both of which have a large impact on the results. We also propose a first-order correction to the issue of kinetic energy transfer between degrees of freedom (DoF). This problem arises when the effective temperatures of translational, rotational, and vibrational DoF are not equal, either due to poor equilibration or reduced system size/time sampling, which are typical problems for ab initio MD. The new scheme enables improved convergence of the results with respect to configurational sampling, by up to one order of magnitude, for short MD runs. To ensure a meaningful assessment, we perform MD simulations of liquid mixtures of water with several other molecules of varying sizes: methanol, acetonitrile, N, N-dimethylformamide, and n-butanol. Our analysis shows that results in excellent agreement with experiment can be obtained with little computational effort for some systems. However, the ability of the 2PT method to succeed in these calculations is strongly influenced by the choice of force field, the fluidicity (hard-sphere) formalism employed to obtain the solid/gas partition, and the assumed combinatorial entropy of mixing. We tested two popular force fields, GAFF and OPLS with SPC/E water. For the mixtures studied, the GAFF force field seems to perform as a slightly better "all-around" force field when compared to OPLS+SPC/E.

FT-IR Spectroscopic study of excess thermodynamic properties of liquid mixtures containing N-methylformamide with 2-alkoxyethanols at various temperatures

Densities, speeds of sound and viscosities were measured for the binary mixtures N-methylformamide (NMF) with 2-alkoxyethanols (2-methoxyethanol (ME), 2-ethoxyethanol (EE) and 2-butoxyethanol (BE)) at T=(303.15 to 318.15) K. These experimental data have been used to calculate excess volume (VE), excess isentropic compressibility (κsE), deviation in viscosity (∆η) and excess Gibbs free energy of activation of viscous flow (G⁎E). The excess partial molar volumes, V̅m,1E and V̅m,2E and excess partial molar volumes V̅m,1°E, and V̅m,2°E at infinite dilution have also been calculated. The variations of these properties with composition of binary mixtures suggest loss of dipolar association, difference in size and shape of the component molecules, dipole–dipole interaction and hydrogen bonding between unlike molecules. The excess parameters have been fitted to the Redlich–Kister equation and the results were analyzed in terms of acid–base interactions, hydrogen bond, and dipole–dipole interaction between unlike molecules. Further, the FTIR spectra have been recorded at 298.15K and found to be useful for understanding the presence of hydrogen bonding between oxygen atom of carbonyl group of N-methylformamide and hydrogen atom of the –OH group of 2-alkoxyethanols molecules in the present liquid mixtures. A good agreement is obtained between excess quantities and spectroscopic data.

FT-IR spectroscopic study of excess thermodynamic properties of liquid mixtures containing benzylalcohol with alkoxyalkanols

Densities (ρ) of pure liquids and their mixtures have been measured at T=298.15K to T=318.15K and 0.1MPa pressure over the entire composition range for the binary mixtures of benzylalcohol (BA) with 2-Methoxyethanol (ME), 2-Ethoxyethanol (EE), 2-Butoxyethanol (BE) by using Rudolph Research Analytical digital densitometer (DDH-2911 model). Further, the speed of sound (u) for the above said mixtures was also measured at T=298.15K and T=308.15K. Values of the experimental density were used to calculate the excess volumes (VE), in turn were compared with Redlich–Kister and Hwang equations. Isentropic compressibility (κS) and excess isentropic compressibility (κSE) were evaluated from experimental speed of sound and density data. Moreover, the experimental speed of sound was analysed in terms of theoretical models, namely Schaaff’s collision factor theory (CFT) and Jacobson’s free length theory (FLT). The experimental results are discussed in terms of intermolecular interactions between component molecules of binary mixtures and also FT-IR Spectroscopic studies.

Thermodynamic Properties of Liquid Mixtures Deduced from Ultrasonic Speed and Viscosity

Excess molar isentropic compressibilities KS, m E and the deviation u of the speeds of sound u from those in the ideal mixtures u, from speeds of sound values are reported. Measurements have been carried out in order to assess the effects of increasing the alkyl chain length of alkane. Further, we have calculated the ideal and excess internal pressures for the binary mixtures 2-butanol + alknae and some other parameters like heat of vaporization, cohesive energy density, solubility parameter, free volume which have been calculated from the internal pressure are also reported. Various physicochemical parameters like intermolecular free length, acoustic impedance, molecular association, relative association, available volume for the pure components as well as for the binary mixtures have also been calculated along with some of their excess counterparts. Results have been discussed in terms of intermolecular interactions.

Kirkwood-Buff Analysis of Liquid Mixtures in an Open Boundary Simulation.

Using the adaptive resolution (AdResS) molecular dynamics scheme, we present a new approach to calculate the thermodynamic properties of liquid mixtures in an open boundary simulation. As a test case, we simulate methanol-water mixtures. We show that Kirkwood-Buff integrals (KBI), which directly connect global thermodynamic properties to microscopic molecular distributions, can be efficiently calculated over a wide range of methanol mole fractions by choosing only a very small (∼3% of total simulation domain) open boundary explicit (all atom) region and a surrounding coarse-grained reservoir that takes care of correct particle fluctuations.

Thermodynamic properties of liquid mixtures containing 1,3-dioxolane and anilines: Excess molar volumes, excess molar enthalpies, excess Gibb's free energy and isentropic compressibilities changes of mixing

Excess molar volumes V E , excess molar enthalpies H E , speeds of sound, u and vapour–liquid equilibrium data of 1,3-dioxolane (i) + aniline or N-methyl aniline or o-toluidine (j) binary mixtures have been measured as a function of composition at 308.15 K. Speeds of sound and vapour–liquid equilibrium data of (i + j) binary mixtures have been utilized to determine isentropic compressibilities changes of mixing, κ S E and excess Gibb's free energy G E . The observed data have been analyzed in term of Graph theory which involves the topology of the mixture constituents. It has been observed V E , H E , κ S E and G E values predicted by Graph theory compare well with their corresponding experimental values.

COSMO-RS: An Alternative to Simulation for Calculating Thermodynamic Properties of Liquid Mixtures

The conductor-like screening model for realistic solvation (COSMO-RS) method has been established as a novel way to predict thermophysical data for liquid systems and has become a frequently used alternative to force field-based molecular simulation methods on one side and group contribution methods on the other. Through its unique combination of a quantum chemical treatment of solutes and solvents with an efficient statistical thermodynamics procedure for the molecular surface interactions, it enables the efficient calculation of many properties that other methods can barely predict. This review presents a short delineation of the theory, the application potential and limitations of COSMO-RS, and its most important application areas.

Theoretical estimations of thermodynamic properties of liquid mixtures by Flory's statistical theory

Flory's statistical theory has been employed for the computation of ultrasonic velocity (u), density (ρ), internal pressure (P i), thermal expansion coefficient (α), isothermal compressibility (β T), adiabatic compressibility (β S), heat capacity at constant pressure (C P), heat capacity at constant volume (C V), heat capacities ratio (γ), pseudo-Gruneisen parameter (Γ), excess volume (V E) and excess heat capacity at constant pressure () at varying temperatures for 10 binary and 5 ternary systems. The binary systems under investigation are: acetonitrile + benzene, benzene + DMF, acetonitrile + DMF, cyclohexanol + cyclohexane, piperidine + tetrahydropyran, piperidine + cyclohexane, tetrahydropyran + cyclohexane, benzene + p-xylene, benzene + p-dioxan, acetone + methyliodide, and the ternary systems are: benzene + chloroform + cyclohexane, toluene + chloroform + cyclohexane, chlorobenzene + chloroform + cyclohexane, dioxane + chloroform + cyclohexane and chlorobenzene + cyclohexane + n-heptane. The results of calculations show that for all the systems under consideration, the calculated values of various thermodynamic parameters show the same trend as observed experimentally. Fairly good agreement is found between theoretical and experimental values. The ultrasonic velocity of liquid mixtures is obtained using the most popular Flory theory without the help of any empirical relation.

Extension of a New Equation of State to the Liquid Mixtures

A new equation of state recently reported for pure liquids has been extended to predict the volumetric and thermodynamic properties of 10 binary mixtures and 1 ternary liquid mixture at different temperatures, pressures, and compositions. A wide comparison with literature experimental data shows the ability of this equation of state to reproduce and predict different volumetric and thermodynamic properties of liquid mixtures. For the binary and ternary mixtures, the composition dependences of the parameters of the equation of state are assumed as quadratic functions of mole fraction. Using these mixing rules, the agreement between the calculated and experimental densities is better than 0.8% for binary mixtures and 3.1% for ternary mixtures.

Clifford V. Heer

Clifford V. Heer