Molal volumes of sucrose in aqueous solutions of NaCl,KCl, or urea at 25°C

The apparent molal volume _v of sucrose in water has been measured at 25°C in the concentration range 0.04–4.4m from precise density measurements. The same property was also determined for dilute solutions of sucrose in mixed aqueous solvents containing NaCl, KCl, or urea. The limiting values _v ^° and the slopesS _v ^* were obtained in each case, and their significance has been discussed briefly. The mean apparent molal volumes _v of the ternary systems were also calculated, and the predictive accuracy of Ward and Millero's modified Young's rule for _v was found to be comparable to that for other electrolyte-nonelectrolyte solutions. For the system H₂O-sucrose-urea, an additivity rule based simply on total molality predicted _v with similar accuracy.Deceased January 15, 1976.     

Volumetric and Viscometric Studies on Sodium Nitrate and Potassium Nitrate in Aqueous and H<Subscript>2</Subscript>O-urea Solutions

Summary.  Density and viscosity of NaNO₃ and KNO₃ in aqueous and in H₂O-urea solutions were determined as a function of electrolyte concentrations at 308, 313, 318, 323, and 328 K, respectively. The apparent molal volume (φ _v ) of the electrolytes were found to be linear functions of the square root of the solute molality (b). The φ _v and data were fitted to the Masson equation [1] by the least square method to obtain the apparent molar volume at infinite dilution (φ _v ^{^}), which is practically equal to the partial molar volume . The viscosity coefficients A and B were calculated on the basis of the viscosity of the solutions and the solvent concerned using the Jones–Dole [2] equation. The activation parameters for viscous flow (ΔG ^≠, ΔS ^≠, and ΔH ^≠) were calculated according to Eyring [3]. The values of for the two systems were also calculated from B-coefficient data. The results were found to be of opposite nature in the two electrolyte systems. Where sodium nitrate showed structure making behaviour both in aqueous and in H₂O-urea solutions, KNO₃ showed structure breaking behaviour in aqueous solutions and structure making behaviour in 5 molal H₂O-urea solutions in the studied temperature range. The behaviour of these two electrolytes in aqueous binary and in aqueous-urea ternary systems are discussed in terms of charge, size, and hydrogen bonding effects. Corresponding author. E-mail: chemistry_ru@yahoo.com Received January 24, 2002; accepted (revised) April 5, 2002     

Apparent molal volumes and heat capacities of some 1:1 electrolytes in anhydrous methanol at 25°C

A flow calorimeter and flow densimeter have been used to measure volume specific heats and densities of solutions of LiCl, LiBr, NaCl, NaBr, KF, KBr, Kl, CsF, and Bu₄NBr in anhydrous methanol at 25°C. The concentrations ranged from approximately 0.01m to close to saturation in some cases. Apparent molal heat capacities _cp and volumes _v have been evaluated and extrapolated to infinite dilution to obtain _cp ^o and _v ^o . Nearly all the heat capacities in methanol are negative. However, with the exception of the lithium halides and Bu₄NBr they are more positive than heat capacities of the corresponding salts in water. The dependence of the heat capacities on ionic radii is generally opposite in methanol solutions from that observed for aqueous solutions. In agreement with others, the _v ^o data indicate that electrostriction in methanol solutions is greater than in aqueous solutions.     

The effect of pressure on the ionization of boric acid in aqueous solutions from molal-volume data

The apparent, φ _v , and partial, \(\bar V_2 \) molal volumes of dilute (0.02 to 0.7m) aqueous boric acid, B(OH)₃, and sodium borate, NaB(OH)₄, solutions have been determined from 0 to 50° C from precision density measurements. The φ _v of boric acid is a linear function of the first power of concentration. For sodium borate, the Debye-Hückel theoretical limiting law slope for the φ _v as a function of the square root of molar concentration is approached at all temperatures studied. The positive deviations at higher concentrations increase with decreasing temperature. The infinite-dilution volume properties of both B(OH)₃ and NaB(OH)₄ indicate that these solutes behave like “structure breakers” between 0 and 50°C (that is ?²φ _v ^° /?T² is negative). The volume change for the ionization of boric acid in water \(\Delta \bar V^\circ \) , is calculated from the volume data at various temperatures. This volume change has been used to estimate the effect of pressure on the ionization of boric acid solutions from 0 to 50°C and 0 to 1000 bars. The calculated effect of pressure on the ionization is in good agreement with direct measurements.     

Ferric borate formation in aqueous solution

Potentiometric analyses indicate that previous investigations have overestimated the stability of ferric borate complexes. The FeB(OH) ₄ ²⁺ formation constant result obtained in the present work is_Bβ ₁ ^* = [FeB(OH) ₄ ²⁺ ][H⁺][Fe³⁺]^-1[B(OH)₃]^-1 = (5.4±0.3) x 10^-3 at 25.0°C and 0.7 molal ionic strength. Our result indicates that solution concentrations of FeOH²⁺ and FeB(OH) ₄ ²⁺ are approximately equal in aqueous solution for boric acid concentrations on the order of 0.3 molal. Fe(B(OH)₄) ₂ ⁺ is a minor species in solution compared to FeB(OH)₄ ²⁺ for conditions such that [B(OH)₃][H⁺]^-1≤ 350, and ferric borate complexation is insignificant in solutions such as seawater where [B(OH)₃] ≤ 4× 10^-4 molal.     

Volumetric and Viscometric Studies on Some Inorganic Electrolytes in Water and in Water-SDS Solution Systems

The apparent molal volumes (φ _v ) of NaCl, NaNO₃, NH₄Cl, CuCl₂, CuSO₄, CoSO₄ and MgSO₄ in water and in water-SDS (Sodium dodecyl sulphate) solutions were determined from density measurements at 308.15, 313.15 and 323.15 K respectively. The limiting apparent molal volume at infinite dilution φ ^o _v which is practically equal to the partial molal volume V ^o ₂) of these electrolytes were found to be higher in water-SDS solution systems than those in water solutions. Viscosity coefficients (A and B) for these systems were also determined by Jones-Dole equation. All these electrolytes, except NH₄Cl exhibit structure making behaviour in water and in water-SDS solutions. Ammonium chloride showed structure breaking properties in water and in 0.01 molar water-SDS solutions. In 0.1 molar SDS solution, it showed structure making behaviour at the temperature range studied. The properties of these electrolytes in water and in water-SDS solution systems have been discussed in terms of the charge, size and hydrogen bonding effect.     

Apparent Molar Volume and Viscosity Studies on Some Carbohydrates in Solutions

 The apparent molar volume (φ_v) and viscosity (η) of L(+)-arabinose, D(+)-galactose, D(−)-fructose, D(+)-glucose, sucrose, lactose, and maltose in water and in 0.1% and 0.3% water-Surf Excel solutions were measured as a function of solute concentrations at 308.15, 313.15, and 323.15 K, respectively. The apparent molar volume (φ_v) of the carbohydrates was found to be a linear function of the concentration. From a φ_v versus molality (b) plot, the apparent molar volume at infinite dilution (), which is practically equal to the partial molar volume at infinite dilutions () of these substances was determined. The viscosity coefficients B and D for the carbohydrates were calculated on the basis of the viscosity of the solutions and the solvent using the Jones-Dole equation. The activation free energy for viscous flow (ΔG ^≠) of the solutions was also calculated using the Eyring equation. The carbohydrates showed structure making behaviour both in water and in water-Surf Excel solutions. When water-Surf Excel solutions and pure water solutions containing carbohydrate molecules are compared, the former were found to be more structured. The behaviour of these solutes in water and in water-Surf Excel solution systems is discussed in the light of solute–solvent interactions.     

Apparent molal volumes of aqueous solutions of bis-tetraalkylammonium salts at 25°C: Methylene-group contribution to the limiting molal volume

Densities of aqueous solutions of a series of polymethonium chloride and bromide salts (CH₃)₃–N–(CH₂)_n–N–(CH₃)₃X₂ have been measured at 25°C. Apparent molal volumes have been calculated, and methylene-group contributions to the limiting apparent molal volumes °_v have been estimated. Constant values of the methylene-group contribution of 16.5 and 17.0 cm³-mole^–1 were obtained for the bromide and chloride salts, respectively. These values are consistent with methylene-group contributions reported for other series of organic electrolytes.     

Apparent Molar Volume and Viscosity Studies on Some Carbohydrates in Solutions

Summary.  The apparent molar volume (φ_v) and viscosity (η) of L(+)-arabinose, D(+)-galactose, D(−)-fructose, D(+)-glucose, sucrose, lactose, and maltose in water and in 0.1% and 0.3% water-Surf Excel solutions were measured as a function of solute concentrations at 308.15, 313.15, and 323.15 K, respectively. The apparent molar volume (φ_v) of the carbohydrates was found to be a linear function of the concentration. From a φ_v versus molality (b) plot, the apparent molar volume at infinite dilution (), which is practically equal to the partial molar volume at infinite dilutions () of these substances was determined. The viscosity coefficients B and D for the carbohydrates were calculated on the basis of the viscosity of the solutions and the solvent using the Jones-Dole equation. The activation free energy for viscous flow (ΔG ^≠) of the solutions was also calculated using the Eyring equation. The carbohydrates showed structure making behaviour both in water and in water-Surf Excel solutions. When water-Surf Excel solutions and pure water solutions containing carbohydrate molecules are compared, the former were found to be more structured. The behaviour of these solutes in water and in water-Surf Excel solution systems is discussed in the light of solute–solvent interactions. Corresponding author. E-mail: chemistry_ru@yahoo.com Received March 19, 2002; accepted (revised) July 31, 2002 Published online February 24, 2003     

The effect of pressure on the ionization of water at various temperatures from molal-volume data1

The apparent molal volumes of dilute (0.002 to 1.0m) aqueous HCl and NaOH solutions have been determined at 0, 25, and 50°C and NaCl solutions at 50°C. The partial molal volumes ( ) of HCl, NaOH, and NaCl solutions have been determined from these apparent molal volumes and other reliable data from the literature. The partial-molal-volume changes ( ) for the ionization of water, H₂OH⁺+OH^–, have been determined from 0 to 50°C and 0 to 1m ionic strength from the partial molal volumes of HCl, NaOH, NaCl, and H₂O. The partial molal compressibilities ( for HCl, NaOH, NaCl, and H₂O have been estimated from data in the literature and used to determine the partial molal compressibility changes ( ) for the ionization of water from 0 to 50°C and 0 to 1m ionic strength. The effect of pressure on the ionization constant of water has been estimated from partial-molal-volume and compressibility changes using the relation from 0 to 50°C and 0 to 2000 bars. The results agree very well with the directly measured values.Contribution Number 1548 from the University of Miami.     

The PVT properties of concentrated aqueous electrolytes IX. The volume properties of KCl and K2SO4 and their mixtures with NaCl and Na2SO4 as a function of temperature

The densities of KCl and K₂SO₄ were measured from dilute solutions to saturation from 5 to 95°C. The data were combined with literature data to produce density and apparent molal volume, V_φ, equations from 0 to 100°C and to saturation. The standard deviations of the density equations were 30×10⁻⁶ g-cm⁻³ and 32×10⁻⁶ g-cm⁻³, respectively, for KCl and K₂SO₄. Pitzer equations were used to fit the V_φ data. The resulting infinite dilute partial molal volumes, V^o, were in reasonable agreement with literature data. The densities of the mixtures of the six combinations of the salts KCL, K₂SO₄ NaCl and Na₂SO₄ were measured at I=2.0 and t=5, 25, 55 and 95°C. The resulting volumes of mixing were fitted to equations of the form

Volumetric studies of some electrolytes in water and in aqueous sodium dodecylsulfate solutions at different temperatures

Abstract  

The apparent molar volumes (φ _v) of KCl, KNO₃, MgCl₂, and Mg(NO₃)₂ have been determined in water and in aqueous sodium dodecylsulfate solutions from density measurements at 303.15, 308.15, 313.15, 318.15, and 323.15 K. The limiting apparent molar volumes (j_v⁰ \varphi_{v}^{0} ) and experimental slopes (S _v) were derived from the Masson equation. The partial molar volume transfer (\Updelta [`(V)]<sub>\texttr</sub> ) (\Updelta {\bar{V}}_{\text{tr}} ) of the electrolytes were obtained from limiting apparent molar volume data from water to aqueous sodium dodecylsulfate solutions and have been interpreted in terms of ion–ion, hydrophilic–hydrophilic, and hydrophobic–hydrophobic interactions on the basis of a co-sphere overlap model. It is shown that the transfer volumes (\Updelta [`(V)]_\texttr ) (\Updelta {\bar{V}}_{\text{tr}} ) are positive and increase with increasing sodium dodecylsulfate concentration for all electrolytes. The structure making or breaking capacities of the electrolytes have been inferred from the sign of [∂² φ _v⁰/∂T ²]_p, i.e., the second derivative of the limiting apparent molar volume with respect to temperature at constant pressure. In water, KCl and KNO₃ exhibit structure breaking and MgCl₂ and Mg(NO₃)₂ exhibit structure making behavior. All the studied electrolytes were found to act as structure makers in aqueous sodium dodecylsulfate solutions.     

Seawater—A test of multicomponent electrolyte solution theories. II. Enthalpy of mixing and dilution of the major sea salts

In a continuing effort to predict the physicochemical properties of seawater from the properties of single aqueous electrolyte solutions, the pairwise heats of mixing at constant molal ionic strength,I=1.0 ional, have been determined for the six possible pairs of salts from the set (NaCl, Na₂SO₄, MgCl₂, MgSO₄) at 30°C. In addition, heats of dilution for two aqueous solutions formed from these salts and havingI=1.0 ional have been determined at 30°C. In order to present the most thermodynamically consistent results, it was found necessary to apply a correction term to the relative apparent equivalent enthalpies given in the literature at 30°C. These correction terms derived from a consideration of published results on heats of dilution at very low concentrations. Further, in order to make predictions for seawater at 25°C, it was deemed desirable to refit existing heat-capacity data. The heats relative apparent equivalent enthalpies for the two mixtures mentioned as well as for seawater. The estimates are based on the theoretical equation of Reilly and Wood for charge-asymmetric mixtures which derives from the work of Friedman. In the most applicable cases, the estimates agree with experimental relative apparent equivalent enthalpies to within 5%. In general, the results substantiate the theoretical equation.Taken in part from the Ph.D. dissertation of W. H. Leung, University of Miami, Miami, Florida 33149.     

Interactions of Some Amino Acids with Aqueous N,N-Dimethylacetamide Solutions at 298.15 and 308.15 K: A Volumetric Approach

The apparent molar volumes, V _φ , of glycine, L-alanine and L-serine were obtained in aqueous 0 to ∼4 mol⋅kg⁻¹ N,N-dimethylacetamide (DMA) solutions from density measurements at 298.15 and 308.15 K. The standard partial molar volume, V _φ ^o, and standard partial molar volumes of transfer, Δ_tr V _φ ^o, were determined for these amino acids. It has been shown that hydrophilic-hydrophilic interactions between charged groups of the amino acids and the —CON= group of DMA are predominant in the case of glycine and L-serine, but for L-alanine the interactions between its side group (—CH₃) and DMA are predominant. An increase in temperature increases the standard partial molar volumes but decreases the transfer volumes of the amino acids. The results have been interpreted in terms of cosphere overlap model.     

Effects of concentration and temperature on molar volumes of L-serine, L-isoleucine, and L-glutamine in aqueous NaCl and NaNO3 solutions

Densities of L-serine, L-isoleucine, L-glutamine in 1.5 mol kg^?1 aqueous NaCl, and NaNO₃ solutions have been measured for several molal concentrations of amino acids at temperatures from 298.15 to 323.15 K. The partial molar volumes (? _v ⁰ ) of L-serine, L-isoleucine, and L-glutamine in 1.5 mol kg^?1 aqueous NaCl/NaNO₃ solutions have been computed using density data. The transfer partial molar volumes (Δ_tr? _v ⁰ ) of L-serine, L-isoleucine, and L-glutamine from water to 1.5 mol kg^?1 aqueous NaCl/1.5 mol kg^?1 aqueous NaNO₃ solutions have been determined at 298.15 K. The trends of variation of ? _v ⁰ and Δ_tr? _v ⁰ with change in temperature have been discussed in terms of ion-ion, ion-hydrophilic, and ion-hydrophobic interactions operative in solutions.     

Apparent Molar Volumes of Symetric and Asymetric Tetraalkylammonium Salts in Dilute Aqueous Solutions

The apparent molar volumes, V_φ of tetramethylammonium, tetraethylammonium, tetrabutylammonium, butyltriethylammonium, dibutyldiethylammonium, and tributylethylammonium bromides have been measured at 298.15K in the concentration range from 0.01 to 0.04mol⋅kg⁻¹. The concentration dependence of V_φ is given using the Redlich and Meyer relation. The apparent molar volume at infinite dilution, V∘_φ, and the empirical constant, B_V, have been calculated. The CH₂-group contribution has been obtained by the additivity rule. The results were interpreted in terms of solute–solvent interactions.     

Volumetric Properties of Amino Acids in Aqueous N-methylacetamide Solutions at 298.15 K

The apparent molar volumes (V _φ ) of glycine, L-alanine and L-serine in aqueous 0 to 4 mol⋅kg⁻¹ N-methylacetamide (NMA) solutions have been obtained by density measurement at 298.15 K. The standard partial molar volumes (V_f⁰)V_{\phi}^{0}) and standard partial molar volumes of transfer (D_trV_f⁰)\Delta_{\mathrm{tr}}V_{\phi}^{0}) have been determined for these amino acids. It has been show that hydrophilic-hydrophilic interactions between the charged groups of the amino acids and the –CONH– group of NMA predominate for glycine and L-serine, but for L-alanine the interactions between its side group (–CH₃) and NMA predominate. The –CH₃ group of L-alanine has much more influence on the value of D_trV_f⁰\Delta_{\mathrm{tr}}V_{\phi}^{0} than that of the –OH group of L-serine. The results have been interpreted in terms of a co-sphere overlap model.     

The Solubility of Boric Acid in Electrolyte Solutions

The solubility of boric acid [B] in LiCl, NaCl, KCl, RbCl, and CsCl was determined as a function of ionic strength (0–6 mol ⋅ kg⁻¹) at 25 ^∘C. The results were examined using the Pitzer equation