Apparent Molar Volume, Isentropic Compressibility, Refractive Index, and Viscosity of DL-Alanine in Aqueous NaCl Solutions

New experimental data at 25^°C for the density, velocity of sound, refractive index, and viscosity of aqueous solutions of DL-alanine and NaCl are reported. The apparent molar volume and isentropic compressibility of DL-alanine in aqueous electrolyte solutions have been calculated from the measured properties. The results show that DL-alanine exhibits a positive volume transfer to solutions of a higher NaCl concentration and a negative apparent isentropic compressibility for DL-alanine in the presence of NaCl. These effects indicate that the apparent volume of DL-alanine is larger in solutions with higher electrolyte concentration and the water molecules surrounding the DL-alanine molecules are less compressible than the water molecules in the bulk solution. The results also show an increase in the viscosity of the solution with an increase in both DL-alanine and NaCl concentrations. These effects are attributed to the two charged groups of DL-alanine and the interactions between the charged groups and the hydrocarbon backbone of DL-alanine with the ions. A model, consisting of a short-range interaction term represented by a virial expansion and a Debye-Hückel term that considers long-range interactions, has been developed to correlate the measured experimental data.     

Thermodynamics of Diglycine and Triglycine in Aqueous NaCl Solutions: Apparent Molar Volume, Isentropic Compressibility, and Refractive Index

New experimental data for the density, speed of sound, and refractive index of aqueous solutions of diglycine + NaCl and triglycine + NaCl have been reported. The apparent molar volume and apparent molar isentropic compressibility of these peptides at various NaCl concentrations have been calculated from the measured properties. The results show that both peptides exhibit a positive volume transfer to solutions with higher NaCl concentrations and a negative apparent isentropic compressibility in the presence of NaCl. These effects indicate that the apparent volumes of the peptide molecules are larger in solutions with higher NaCl concentrations and that the water molecules around the peptide molecules are less compressible than the water molecules in the bulk solvent. These effects are attributed to the doubly charged nature of the peptides and the interactions between the charged groups and hydrocarbon backbone of peptides with the ions.     

pH值对亮黄水溶液及CTAB胶束溶液共振Raman光谱的影响

我们曾研究了黑皂膜的界面性质,为深入了解pH对偶氮苯类化合物在水溶液中及胶束表面上结构变化的影响,本文选用亮黄(BY)为谱学探针,仔细考察了其水溶液及溴化十六烷基三甲铵(CTAB)胶束溶液的共振Raman光谱,根据谱带指认,描述了由酸碱性导致的BY分子的结构变化,其中包括共振体间平衡和酸碱平衡。     

Density and Sound Velocity Studies of Aqueous Solutions of Tetradecyltrimethylammonium Nitrate at Different Temperatures

The density and ultrasound velocity of aqueous solutions of tetradecyltrimethylammonium nitrate were measured in the temperature range of 15 to 35°C in 5°C intervals. The concentration range covered the premicellar and micellar regimes. By assuming a pseudophase separation model for the micellar system, we applied the densitometric data to estimate the apparent molar volumes and the apparent thermal expansibility coefficients of the surfactant in monomeric and micellar forms. Ultrasound velocity and density data enabled us to estimate the isentropic compressibility of the surfactant in both forms. The results are compared with relevant literature data for alkyltrimethylammonium bromides.     

Excess Molar Volumes,Viscosity Deviations and Isentropic Compressibility of Binary Mixtures Containing 1,3-Dioxolane and Monoalcohols at 303.15 K

The excess molar volume (V ^E), viscosity deviations (Δη) and Gibbs excess energy of activation for viscous flow (G^∗E) have been investigated from density (ρ) and viscosity (η) measurements of eight binary mixtures of 1,3-dioxolane with methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, and i-amyl alcohol over the entire range of mole fractions at 303.15 K. The viscosity data have been correlated with the Grunberg and Nissan equation. Furthermore, excess isentropic compressibilities (K_S^E) have been calculated from ultrasonic speed measurements of these binary mixtures at 303.15 K. The deviations have been fitted by a Redlich–Kister equation and the results are discussed in terms of molecular interactions and structural effects. The excess properties are found to be either negative or positive depending on the molecular interactions and the nature of the liquid mixtures. The systems studied exhibit very strong cross association through hydrogen bonding.     

Er2O3的光致发光光谱,吸收光谱和Raman光谱

在可见激光的激发下,Ｅｒ２Ｏ３粉晶样品的Ｒａｍａｎ光谱易受Ｅｒ＾３＋光致发光光谱的干扰。本文利用同一Ｒａｍａｎ光谱仪测得Ｅｒ２Ｏ３的高分辨可见光吸收光谱和激发光谱。     

Experimental Densities, Speeds of Sound, Isentropic Compressibilties and Shear Relaxation Times of CaSO4·2H2O + CaCl2 + H2O and CaSO4·2H2O + NaCl + H2O Systems at Temperatures 30 and 35 °C

Speeds of sound, u, have been measured as a function of concentration for the systems, CaSO₄·2H₂O +CaCl₂ + H₂O and CaSO₄·2H₂O + NaCl + H₂O, at temperatures of 30 and 35 °C. Derived parameters such as the isentropic compressibility, κ _S , and the shear relaxation time,τ,were calculated using the experimental speed of sound data in combination with viscosity values from our earlier work. Results have been compared with those of the CaCl₂+ H₂Oand NaCl + H₂O systems reported in literature,to examine the effect of adding CaSO₄·2H₂O(s).Values of κ _S for the system,CaSO₄·2H₂O + CaCl₂+H₂O,are smaller compared with those for the CaCl₂+ H₂O system.Values of τ are lower at lower concentrations and then cross over in a narrow concentration region.Values of κ _S for the system,CaSO₄·2H₂O+NaCl+H₂O, are also smaller when compared with those forthe NaCl +H₂O system.For this system the τ values are higher. These τ values reach a minimum at a certain concentration of NaCl in the solution and then increase with further increases in concentration.The influenceof solvent-separated and/or solvent-shared ion pairs plays a dominant role at higher concentrations for both systems.Results have been interpreted and discussed in terms of the expansion and contraction of the primary hydration shell of the ionic species present in the studied systems.     

Raman Spectroscopy of Aqueous ZnSO4 Solutions under Hydrothermal Conditions: Solubility, Hydrolysis, and Sulfate Ion Pairing

Raman spectra have been measured for aqueous ZnSO₄ solutions under hydrothermal conditions at steam saturation to 244°C; solubility has been recorded as a function of temperature from 25 to 256°C. The high-temperature Raman spectra contained two polarized bands, which suggest that a second sulfato complex, possibly bidentate, is formed in solution, in addition to the 1:1 zinc(II) sulfato complex, which is the only ion pair identified at lower temperatures. Under hydrothermal conditions, it was possible to observe the hydrolysis of the zinc(II) aquo ion by measuring the relative intensity of bands due to SO ₄ ^2– and HSO ₄ ^– according to the equilibrium reaction Zn(OH₂)₆]²⁺ + SO ₄ ^2– [Zn(OH₂)₅OH]⁺ + HSO ₄ ^– The precipitate in equilibrium with the solution at 210°C could be characterized as ZnSO₄ · H₂O (gunningite) by x-ray diffraction (XRD) and Raman and infrared spectroscopy. At 244°C the equilibrium precipitate could be identified as ZnSO₄ (zincosite).     

1H-NMR Relaxation of Water Molecules in the Aqueous Microcrystalline Cellulose Suspension Systems and Their Viscosity

An intensive study for aqueous microcrystalline cellulose (MCC) suspensions was carried out in view of the relationship between a viscosity and a 1H spin-spin relaxation time (T2) of water. An investigation was carried out for four suspension systems with the different particle size distributions. The proton mole ratio () of bound water against MCC particles and T2 of bound water (T2,b) were evaluated from the T2 values obtained by Carr-Purcell- Meiboom-Gill (C.P.M.G) method and those by solid echo method, respectively. As a result of these analyses, the T2,b value for the aqueous MCC suspension was evaluated as 5 × 10–3 s and it was found that the system having a larger tended to show a higher viscosity. By relating the above results to the observation of the suspensions by an optical microscope, it was concluded that a network formed by MCC particles plays an important role in generating a high viscosity of MCC suspension, and that an averaged mobility of water molecules is sensitively affected by the network structure.     

Raman and Infrared Spectra, Ab Initio Calculations, Normal Coordinate Analysis, and Conformational Stability of 2-Methoxypropene

The Raman (3500–40 cm^–1) and infrared (3500–70 cm^–1) spectra of gaseous and solid 2-methoxypropene, CH₃O(CH₃)C=CH₂, and the isotopomers, CD₃O(CH₃)C=CH₂ and CH₃O(CD₃)C=CD₂ have been recorded. In addition, the Raman spectra of the liquids have been recorded with qualitative depolarization measurements. All of these data indicate that only one conformer is present in the fluid phases at ambient temperature and this form is the cis conformer, which remains in the solid. Assignments are provided for the fundamentals of all three isotopomers for the cis conformer with C_s symmetry. The far-infrared spectra of all three isotopic species have been recorded at a resolution of 0.1 cm^–1 in the gas and 1.0 cm^–1 in the solid. The parameters of the potential function governing the asymmetric torsion are determined to be V₃ = 1485 ± 9 cm^–1 and V₆ = –55 ± 4 cm^–1 for the d₀ compound, where only two terms were determined, since a second conformer was not evident. The barrier to internal rotation for the methyl group attached to the oxygen atom is 1370 ± 8 cm^–1 and the C—CH₃ barrier is 772 ± 5 cm^–1. Ab initio calculations with full electron correlation have been carried out by the perturbation method to second order to obtain the equilibrium structural parameters, harmonic force constants, fundamental frequencies, infrared intensities, Raman activities, depolarization values, and conformational stability. The predicted values have been compared to the experimental values where appropriate.     

Aqueous solutions of sodium methylsulfate by Raman scattering,NMR, ultrasound,and density measurements

Dynamic properties of sodium methylsulfate were investigated by means of NMR and Raman spectroscopies. The concentration dependence of the spin-lattice relaxation times of²³Na in aqueous solutions of sodium methylsulfate show no detectable specific interactions between sodium and methylsulfate ions. Raman band profiles of the S-O stretching mode of methylsulfate ion in aqueous solution show asymmetry above about 3.0 mol-dm^–3. Furthermore, the proton spin-lattice relaxation rates of the methylsulfate ion in D₂O increase linearly up to about 3.0 mol-dm^–3, but above this concentration they deviate from linearity.These experimental results indicate that dynamic properties of methylsulfate ion are affected by ion-water interactions. Raman band asymmetry is attributed to the non-uniformity of the distribution of water molecules around the methylsulfate ion. This interpretation is supported by the theory developed by Knapp and Fischer. The distortion of the distribution of water molecules around ions is also discussed on the basis of the overlap of the hydration layer around methylsulfate ion which is estimated by the measurement of sound velocity and density.     

Experimental Vapor Pressures and Derived Thermodynamic Properties of Aqueous Solutions of Lithium Nitrate from 423 to 623 K

Vapor pressures of six aqueous lithium nitrate solutions with molalities of (0.181, 0.526, 0.963, 1.730, 2.990, and 5.250) mol-kg^–1 have been measured in the temperature range 423.15–623.15 K with a constant-volume piezometer immersed in a precision liquid thermostat. The static method was used to measure the vapor pressure. The total uncertainty of the temperature, pressure and composition measurements were estimated to be less than 15 mK, 0.2%, and 0.014%, respectively. The vapor pressures of pure water were measured with the same apparatus and procedure to confirm the accuracy of the method used for aqueous lithium nitrate solutions. The results for pure water were compared with high-accuracy P_S–T_S data calculated from the IAPWS standard equation of state. Important thermodynamic functions (activities of water and lithium nitrate, partial molar volumes, osmotic coefficient, excess relative partial molar entropy, and relative partial molar enthalpy values of the solvent) were derived using the measured values of vapor pressure for the solution and pure water. The measured and derived thermodynamic properties for solutions were compared with data reported in the literature. The present results are consistent with most previous reported thermodynamic data for the pure water and H₂O + LiNO₃ solutions at low temperatures.     

meso-四-(对甲氧苯基)卟啉与锌、镉、铅的导数光谱及CPA矩阵法同时测定该三元素的研究

本文研究了meso-四-(对甲氧苯基)卟啉与Zn~(2+)、Cd~(2+)、Pb~(2+)的共显色条件和导数光谱行为,并提出用四阶导数光谱同时测定该三组份含量的计算分析方法。在Tween-80存在下,在0.06mol/L的NaOH介质中,于沸水浴上加热30min,Zn、Cd、Pb混合体系能较好地显色。其表观摩尔吸光系数在10~5数量级以上,四阶导数光谱摩尔响应系数仍在10~6数量级以上。通过计算机精选工作波长后,用四阶导数CPA法同时测定合成样品中的锌、镉、铅〔Zn:Cd:Pb=0.05:2:4～1.5:0.05:4～0.2:3:0.2～7.5:0.4:0.5(μg/25ml)〕回收率在90～110(％)之间。     

ChemInform Abstract: Transoid,Ortho, and Gauche Conformers of n‐Si4Cl10: Raman and Mid‐IR Matrix‐Isolation Spectra.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Experimental Study of the Effect of Temperature,Pressure and Concentration on the Viscosity of Aqueous NaBr Solutions

The viscosity of 10 (0.049, 0.205, 0.464, 0.564, 0.820, 1.105, 1.496, 2.007, 2.382, and 2.961 mol ċ kg⁻¹) binary aqueous NaBr solutions has been measured with a capillary-flow technique. Measurements were made at pressures up to 40 MPa. The range of temperature was 288–595 K. The total uncertainty of viscosity, pressure, temperature and composition measurements were estimated to be less than 1.6%, 0.05%, 15 mK, and 0.02%, respectively. The effect of temperature, pressure, and concentration on viscosity of binary aqueous NaBr solutions were studied. The measured values of the viscosity of NaBr(aq) were compared with data, predictions and correlations reported in the literature. The temperature and pressure coefficients of viscosity of NaBr(aq) were studied as a function of concentration and temperature. The viscosity data have been interpreted in terms of the extended Jones–Dole equation for the relative viscosity (η/η₀) to calculate accurately the values of viscosity A- and B-coefficients as a function of temperature. The derived values of the viscosity A- and B-coefficients were compared with the results predicted by the Falkenhagen–Dole theory of electrolyte solutions and calculated with the ionic B-coefficient data. The physical meaning parameters V and E in the absolute rate theory of the viscosity and hydrodynamic molar volume V k were calculated using the present experimental viscosity data. The TTG model has been used to compare predicted values of the viscosity of NaBr(aq) solutions with experimental values at high pressures.     

ChemInform Abstract: Crystal Structure,Electronic Structure,and Temperature-Dependent Raman Spectra of Tl[Ag(CN)2]: Evidence for Ligand-Unsupported Argentophilic Interactions.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Densities,Apparent Molar Volumes and Viscosities of Concentrated Aqueous NaNO<Subscript>3</Subscript> Solutions at Temperatures from 298 to 607 K and at Pressures up to 30 MPa

Densities of four (2.124, 2.953, 5.015 and 6.271 mol-kg⁻¹) and viscosities of eight (0.265, 0.503, 0.665, 1.412, 2.106, 2.977, 5.015 and 6.271 mol-kg⁻¹) NaNO₃(aq) solutions have been measured with a constant-volume piezometer immersed in a precision liquid thermostat and using capillary flow techniques, respectively. Measurements were made at pressures up to 30 MPa. The temperature range was 298–607 K for the density measurements and 298–576 K for the viscosity measurements. The total uncertainty of density, viscosity, pressure, temperature and composition measurements were estimated to be less than 0.06%, 1.6%, 0.05%, 15 mK and 0.02%, respectively. The temperature, pressure and concentration dependence of density and viscosity of NaNO₃(aq) solutions were studied. The measured values of density and viscosity of NaNO₃(aq) were compared with data and correlations reported in the literature. Apparent molar volumes were derived using the measured density values. The viscosity data have been interpreted in terms of the extended Jones–Dole equation for strong electrolytes. The values of the viscosity A-, B-, D- and F-coefficients of the extended Jones–Dole equation for the relative viscosity (η/η₀) of NaNO₃(aq) solutions were evaluated as a function of temperature. The derived values of the viscosity A- and B-coefficients were compared with the results predicted by Falkenhagen–Dole theory of electrolyte solutions and calculated with the ionic B-coefficient data.     

ChemInform Abstract: Theoretical Study of Binding Interactions and Vibrational Raman Spectra of Water in Hydrogen‐Bonded Anionic Complexes: (H2O)n‐ (n = 2 and 3), H2O×××X‐ (X: F,Cl, Br,and I), and H2O×××M‐ (M: Cu,Ag, and Au).

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.