Electrostriction Volumes Research Articles

Thermodynamic parameters of solvation and volumes of nano Cu(NO3)2·2.5H2O in different concentrations of DMF – Water mixed solvents

• Molar solubilities and solubility products of nano copper nitrate are measured. • Solvation thermodynamic parameters of Cu(NO 3 ) 2 ·2.5H 2 O are calculated. • Effect of mole fraction of DMF and temperature on solvation thermodynamic parameters of Cu(NO 3 ) 2 ·2.5H 2 O are studied. • Different types of volumes are calculated. Solvation thermodynamic parameters of nano copper nitrate hemi pentahydrate Cu(NO 3 ) 2 ·2.5H 2 O in mixed N,N-Dimethylformamide (DMF) – water solvents at different temperatures were discussed. The molar solubilities of nano copper nitarte Cu(NO 3 ) 2 ·2.5H 2 O in different ratios of DMF and water were measured at 293.15, 303.15, 313.15 and 323.15 K. The different solvation parameters such as solubility products, Gibbs free energies of solvation, activity coefficients, enthalpies and entropies of solvation were calculated from the values of molar solubilities of nano copper nitrate. Different types of volumes, molar volume (V M ), Van der Waals volume (V W ) and electrostriction volume (V e ) were calculated for Cu(NO 3 ) 2 ·2.5H 2 O in DMF – H 2 O mixed solvents at different temperatures.

How increasing pressure affects the ion hydration structure and shell properties at ambient temperature

This work deals with the effect of increasing pressure at 298.15 K on the structure and hydration shell properties of ions in infinitely diluted solutions. Results were obtained from NPT Monte Carlo simulations at various pressures, from 1 atm up to 8000 atm, for some alkali metal, alkaline earth and halide ions in TIP4P water. As pressure increases, the ion-O and the ion-H radial distribution functions (rdfs) are subjected to changes to differing extents depending on both the charge and the size of the ion. The first peak of the ion-O rdf is shifted to a shorter distance from the ion for Cs+, Br− and I−, while in the other cases there is no evidence of shortening. In contrast, for the alkaline earth ions, the most prominent effect is the decrease in the height of the first peak. Minima positions of the ion-O rdfs were used to define the first and the second hydration shells at a given pressure. Water dipole orientation with respect to the radial direction was examined, showing that at higher pressures the ion-dipole interaction becomes less attractive than at 1 atm. A much less favorable orientation was found for waters in the first shell of halide ions. Shell properties were computed from definite integrals of the ion-O rdfs, such as the coordination number and the shell contribution to the excess volume. For the first hydration shell, apart from Ca2+, there is a significant increase in the coordination number upon increasing pressure. This effect becomes more important the larger the ion size is and this is very significant for alkali metal and halide ions. In the case of I− the gap observed between 4 katm and 5 katm reflects the striking effect of increasing pressure on the shell definition. The coordination number remains almost constant when using an alternative boundary for the shell. This was suggested by the radial distribution of water-dipole orientations. Shell excess volume contributions are discussed by examining their dependence on pressure. Electrostriction is shown for the first shell, while the second shell's contribution to the excess volume is positive. At a higher pressure, the shell electrostrictive volume per water molecule is always less than at 1 atm. The greatest effect is shown for the first shell of alkaline earth. The effect of a different shell boundary is examined on the shell quantities of halide ions.

ANTIBIOTIC OXYTETRACYCLINE SOLVATION INTERِِCTIONS WITH ETHANOL-AQUEOUS MIXTURS AT DIFFERENT TEMPERATURES

Abstract: The solubility is one of the vital parameters to attain the specified concentration of the drug in circulation for the desired (anticipated) pharmacologic response. This work aimed to calculate ion-solvent interaction, the density of ethanol-water (EtOH-H2O) mixtures; the density of oxytetracycline (OTC) saturated solutions, different volumes of solvation (Van der Waals volume, molar volume and electrostriction volume and solvated radii (ro)) from solubility data. It was found that; the activity coefficient (γ_±) of OTC were decreased by increasing the EtOH content in (EtOH-H2O) mixture used and also the logγ_± decrease within the rise in temperature. The densities and also the molar volume of OTC decrease by increasing the quantitative ratio of EtOH and also was increased by rising in temperature. The electrostriction volumes and therefore the solvated radii (ro) of OTC are increased as the EtOH content increase and also are increased by the rise in temperature.

Electrostriction of water and lower alcohols around ammonium nitrate – Volumetric approach

Abstract Physicochemical properties and nature of the interactions in solutions of ammonium nitrate in water or lower alcohols (methanol, ethanol and n-propanol) have been investigated. The density was measured in the temperature range from T = (293.15 to 313.15) K for {NH4NO3 + H2O} and {NH4NO3 + MeOH} binary mixtures and in temperature range T = (293.15 to 323.15) K for {NH4NO3 + EtOH} and {NH4NO3 + n-PrOH} at atmospheric pressure (p = 1·105 Pa). From experimental densities, the apparent molar volumes and partial molar volumes in a whole concentration range, as well as at infinite dilution were obtained. According to volumetric results obtained for solutions of NH4NO3 in short-chain alcohols and water, values for the electrostrictive volume of the ammonium nitrate, V ¯ el , solvation number, n, and ionic transfer volumes between solvents, Δ t V ¯ o ( NH 4 NO 3 ,w → s ) , are obtained and discussed. Based on these values and features the electrolyte effect on surrounding molecules were estimated and discussed.

Barium Diphenylamine-4-Sulfonate (BDPA) Ion-Ion Interactions and Solvation Volumes in Acetonitrile–Water Mixed Solvents

The aim of this work is to calculate ion-ion interaction, density of organic-aqueous mixtures of Acetonitrile-water (AN-H₂O), density of saturated solutions of BDPA, salvation volumes (Van der Waals volume V_M, molar volume V_M and electrostriction volume V_e) and solvated radii (r_o) from solubility experiments. It was found that values of the log activity coefficient (<i>γ</i></sub>+_{) of BDPA in (AN-H2O) mixture were decreases by increasing in the content of the organic solvent used. The values of the log <i>γ</i>}+<sub> found to decrease with the increase in temperature. The densities and the molar volumes of the saturated solutions of BDPA decrease by increasing ratio of AN and also increases by increasing in temperature. All the electrostriction volumes calculated for BDPA having negative values. The electrostriction volumes increase in negativity on increasing the percentages of the organic solvent. The solvated radii of BDPA are increased as the organic solvent content increase and as the temperature increase.

Solvation Numbers of Divalent Metal Salts and Ions in Some Non-aqueous Solvents

The few data available so far for the solvation numbers of divalent metal salts in non-aqueous solvents at infinite dilution are augmented by values in methanol, acetonitrile, N,N-dimethylformamide, and dimethylsulfoxide for alkaline earth and first row transition metal salts at 298.15 K. These were obtained from the isothermal compressibilities and the molar electrostriction volumes, as appropriate, with good agreement where comparable. Solvation numbers were evaluated for the individual ions, where possible. The intrinsic volume of the triflate anion was evaluated for this purpose.

Electrostriction of Several Nonaqueous Solvents under Ambient Conditions and Solvation Numbers of Ions in Them.

The diminution of the mean molar volume on electrostriction, ΔelVS, in the large electrical field of ions solvated by several solvents that are useful for the dissolution of electrolytes is presented. The solvents dealt with are ethanol, trifluoroethanol, 1,2- and 1,3-propanediols, glycerol, 2-butanone, 1,1- and 1,2-dichloroethane, pyridine, benzonitrile, nitromethane, nitrobenzene, formamide, and dimethylformamide. The inverse dependence of the relative molar electrostriction volume on the dipole moment of the solvents is suggestive of the fact that the larger the polarity of the solvents, the more they are able to withstand the compressive effect of the electrical field. The implications of this decrease in solvent volume with regard to the solvation number of ions in these solvents have been dealt with.

Conductometric Studies of Ionic Association of Divalent Asymmetric Electrolyte Cu(NO3)2 with Kryptofix -22 in Mixed (MeOH-DMF) Solvents at Different Temperatures

On using conductometric technique, new equation is applied for calculation of apparent association constant (KA). The association constant (KA) were studied and calculated for Cu(NO3)2 in absence and presence of Kryptofix-22 (1,7,10,16 tetra oxa 4,13 diaze cyclo octa decane) in mixed (MeOH-DMF) solvents at different temperatures. From the experimental results, the molar conductivities (Λ ) is evaluated. The limiting molar conduclivities (Λ o) were also calculated by using Shedlovsky and Fouss-Kraus extrapolation method. The Gibbs free energies of association (∆ GA) were estimated in absence and presence of Kryptofix-22, and from these date, we calculated ∆ G (Complexing). We also calculated the value of enthalpy (∆ HA) and entropy (∆ SA) For Cu(NO3)2 in absence and presence of Kryptofix-22. In addition to (KA), (∆ GA), (∆ HA), and all the previous results, the molar volume (V), solvated radius (rs), Van der Waals (Vw), electrostriction Volume (Ve) and apparent molar volume ( V φ )were also calculated. All the results were discussed. Keywords Conductometry, Kryptofix-22, Association, Cu(NO3)2, (MeOH-DMF)solvents, Van der Waals volume, Molar solvated volume, Electrostriction volume, Apparent molar volume, Limiting conductance, Free energy of association

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.

Influence of polyvinylalcohol on the solvation volumes of FeCl3 and CoCl2 in aqueous ethanol solutions

The effect of polyvinylalcohol (PVA) on molar, Van-der Waals and the electrostriction volumes of FeCl3 and CoCl2 in pure H2O and 50% ethanol (EtOH)–water mixtures was studied. Excess volumes were also calculated and their values were discussed in terms of Pierotti theory (Scaled Particle Theory). Different theoretical energy values were calculated to explain the following parameters: volumes, dispersion, induction energies and 6-12 Lennard–Jones parameters. The increase and the decrease in excess volumes of FeCl3, CoCl2 in the absence and in the presence of polyvinyl alcohol in both aqueous and 50% EtOH–H2O mixtures were also discussed in terms of the increase or decrease of different interaction energies.

Electrostriction, Ion Solvation, and Solvent Release on Ion Pairing

The theoretical mean molar electrostriction volume of electrolytic solvents, DeltaVel(solvent), was calculated from their properties: the relative pressure derivatives of the density (the compressibility) and permittivity and their second pressure derivatives. The molar electrostriction caused by ions at infinite dilution was taken as the differences of their standard partial molar volumes in the solution and their intrinsic volumes: DeltaVel(ion) = Vinfinity(ion) - Vin(ion). The ratio ninfinity = DeltaVel(ion)/DeltaVel(solvent) then represents the solvation number of the ion in the solvent at infinite dilution. Similarly, from the molar volume change on ion pair formation, DeltaVip, the ratio Deltanip = DeltaVip/DeltaVel(solvent) represents the number of solvent molecules released thereby. These values were tabulated for those solvents, ions, and ion pairs for which the relevant information could be found, the extension to nonaqueous solvents not having been attempted previously.

Volumetric Parameters of Interaction of Monosaccharides (D-xylose, D-arabinose, D-glucose, D-galactose) with NaI in Water at 298.15 K

Densities for monosaccharide (D-xylose, D-arabinose, D-glucose, D-galactose)–NaI–water solutions were measured at 298.15 K and were used to calculate the apparent molar volumes of these saccharides and NaI. Infinite dilution apparent molar volumes for the saccharides (VΦ,S∘) in aqueous NaI and those for NaI (VΦ,E∘) in aqueous saccharide solutions and partial molar volumes of the saccharides (VS) and NaI (VE) at each composition have been evaluated, together with the standard transfer volumes of the saccharides (Δtr VS∘) from water to aqueous NaI and those of NaI (ΔtrVE∘) from water to aqueous saccharide solutions. It was shown that the Δ tr VS∘ and ΔtrVE∘ values are positive and increase with increasing co-solute molalities. Volumetric parameters indicating the interactions of NaI with saccharides in water were also obtained and applied to explore the interactions between saccharides and NaI in water. A comparison of the νES value for NaI with those for NaCl and NaBr showed that for a given saccharide, except for glucose, the νES value for NaBr is the largest of three sodium halides (NaCl, NaBr and NaI). These were interpreted in terms of the apparent molar electrostriction volumes (Δ Ve) and the structure interaction model.

The standard partial molar volumes of ions in solution: Part 1. The volumes in single non-aqueous solvents at 298.15 K

The standard partial molar volumes of univalent ions in a variety of solvents are calculated as the sum of their intrinsic volume and a (negative) electrostrictive volume or, for tetraalkyl- or aryl ions, structural contributions. The shell-by-shell calculation of the electrostriction according to Marcus and Hefter takes into account the mutual dependence of the relative permittivity and the electrical field strength of the solvent around the ion. It leads to good agreement between the calculated and the experimental values for all solvents, both dipolar aprotic and hydrogen bonding, for which data for univalent ions are available. In particular, this approach permits an independent estimation of the standard partial molar volumes of alkali metal halides in anhydrous formic acid, not included in the former comparisons.

Time-resolved photoacoustic calorimetry of aqueous peroxodisulfate photolysis in the presence of nitrite anions

The photodissociation of aqueous peroxodisulfate in the presence of nitrite anions was studied between 282 and 292 K by time-resolved photoacoustic calorimetry at 266 nm. Aqueous peroxodisulfate was chosen as the calorimetric reference, thus enabling the measurement of the enthalpy and volume changes associated with the reaction of the photoproduced sulfate radicals with nitrite anions to form SO4−2 and NO2 in the submicrosecond time range. The enthalpy change obtained (−192 ± 19 kJ mol−1) is consistent with available thermochemical data for related species. The interpretation of the measured reaction volume (−13.8 ± 0.7 mL mol−1) points to the ionic charge accumulation on the sulfate anion as the dominating change causing the contraction of the solvent. The comparative analysis of our experimental result and data for partial molar volumes and electrostriction volumes of electrolytes, reinforces the concept that particularly in the case of water, more realistic models for the solvent are needed involving structure rather than continuous features.

Thermodynamics of Electron Attachment to Pyrimidine and Styrene in Supercritical Ethane

The reaction of excess electrons with pyrimidine and styrene was studied in supercritical scheme. The equilibrium constant for attachment was large when the solute was pyrimidine and small for styrene, although their electron affinities are comparable. At pressures above 100 bar, the rate constant for electron attachment to pyrimidine ({kappa}{sub a}) was time resolved using the short pulse of the laser-electron accelerator facility (LEAF). The rate constant, {kappa}{sub a}, is large and nearly independent of pressure and temperature; thus, the volume of activation is close to zero. At lower pressures, the equilibrium constants for this reaction were derived from the changes in the mobility of excess electrons. The free energy is a function of the polarization energy, which was evaluated with a compressible continuum model. The small equilibrium constant in the case of styrene is attributed to a smaller polarization energy. Values of {Delta}V{sub r}, obtained from changes of {Delta}G{sub r} with pressure, range from {minus}9.0 to {minus}0.4 L/mol. The observed volume changes are compared to electrostriction volumes calculated by the model. Electron attachment occurs with a large decrease in entropy associated with clustering of ethane molecules around the ion formed. Observed values of {Delta}S{sub r} are comparable to expectedmore » values calculated from {Delta}S{sub r} = ({alpha}/{chi}T){Delta}V{sub r}.« less

Electron Attachment to CO2 in Supercritical Ethane

Thermal electrons attach reversibly to CO2 in supercritical ethane. The equilibrium constants range from 40 to 2 × 104 m-1 for pressures from 50 to 220 bar at 33 and 37 °C. The attachment rate increases and the detachment rate decreases as the pressure increases. The lifetime of CO2- is between 20 and 100 ns in the high-pressure range. The reaction volume changes more than an order of magnitude, from −20.0 to −0.5 L/mol over the pressure and temperature ranges studied. The activation volume is approximately 50% of the reaction volume. Electrostriction volumes of the CO2- ion, calculated by a compressible continuum model, account for the main part of the observed reaction volumes. The calculation shows that the high-density region around each CO2- extends to 1 nm.

Effective Ionic Radii and Hydration Volumes for Evaluation of Solution Properties and Ionic Adsorption

Evaluation of effective ionic radii and corresponding individual hydrated-ion volumes provides data required for interpretation of various ion-specific solution properties and for understanding of specificity of ion adsorption at electrode and colloid interfaces. Principles involved in assignment of intrinsic ionic radii and hydrated-ion volumes are comparatively reviewed and examined as a basis for discussion of electrostriction volume changes. Three examples are given of applications of procedures for evaluation of individual hydrated-ion radii and volumes: (a) partial molal volumes and isentropic compressibilities of a series of oxyanions of various structures; (b) steric effects in hydration of alkylammonium and pyridinium cations; and (c) role of ion-hydration effects in specificity of chemisorption of electron donative anions at electrode surfaces.

Studies of e − + CO 2 ⇌ CO 2− equilibria in hexamethyldisiloxane and bis(trimethylsilyl) methane

Electrons react reversibly with CO 2 in bis(trimethylsilyl)methane and hexamethyldisiloxane. This reaction is studied as a function of both temperature and pressure. The ground state energies of electrons are deduced and are quite low consistent with the observed high electron mobility. A linear dependence of the log of the attachment rate on the free energy of reaction is observed. The dependence of the equilibrium constant on pressure indicates the electrostriction volume of CO 2 − to be ≈−200 cm 3/mol in these liquids.

Electron mobility in liquid n-hexane/2,2-dimethylbutane mixtures under high pressure

The effect of pressure on the electron mobility in mixtures of n-hexane and 2,2-dimethylbutane was studied over the whole concentration range. The variation of mobility with pressure is discussed in terms of a two-state model, and provides information on the volume changes occurring on localization. The observed volume changes are interpreted as the difference between the cavity volume and the electrostriction volume of the localized electron.

Separation of Intrinsic and Electrostrictive Volume Effects in Redox Reaction Volumes of Metal Complexes Measured Using High-Pressure Cyclic Staircase Voltammetry.

Redox reaction volumes, obtained by high-pressure cyclic voltammetry, are reported for a selection tris(diimine), tris(diamine), hexaammine, and hexaaqua couples of Fe(III/II), Cr(III/II), Ru(III/II), and Co(III/II). Separation of the intrinsic and electrostrictive volume contributions for these couples has been achieved, some in both aqueous and acetonitrile solutions. For the Co(phen)(3)(3+/2+) system, the intrinsic volume change is estimated to be +15.3 +/- 2.1 cm(3) mol(-)(1) (based on measurements in water) and +16.5 +/- 2.0 cm(3) mol(-)(1) (in acetonitrile). For the Co(bipy)(3)(3+/2+) system, values are +12.7 +/- 1.4 cm(3) mol(-)(1) (in water) and +15.5 +/- 2.5 cm(3) mol(-)(1) (in acetonitrile). Using these experimentally determined intrinsic contributions, a simple structural model suggests that the intrinsic volume change for these reactions can be described using the change in effective volume of a sphere with radius close to that of the coordinating-atom-metal bond length. Electrostrictive volume changes for the 3+/2+ complex-ion couples are a function of solute size and coordinated ligands. For Ru(H(2)O)(6)(3+) and Fe(H(2)O)(6)(3+) reduction, volume behavior is significantly different from that of the other systems studied and can be rationalized in terms of possible H-bonding interactions with surrounding solvent which affect the electrostrictive volume changes but which are not available for the ammine and other complexes studied.