Mole Of Solute Research Articles

Volumetric, viscometric and refractive index study of amino acids in mixed solvents at 308.15 K

Densities, ρ, viscosities, η and refractive indices n D for solutions of (0.10, 0.20, 0.30, 0.40 and 0.50 M) glycine (Gly), DL-alanine (Ala) and L-serine (Ser) in aqueous 1-propanol (10 and 30% v/v) at 308.15 K have been determined. These data have been used to calculate apparent molar volumes, φv, partial molar volumes, and Falkenhagen and Jones–Dole coefficients, A and B, respectively. Free energies of activation of viscous flow, and per mole of solvent and solute, respectively, were obtained by using transition state theory to the B-coefficient data. The molar refractive indices, R D were calculated from the experimental values of refractive indices for all the three amino acids + aqueous 1-propanol ternary mixtures. These parameters were used to discuss the solute–solute and solute–solvent interactions and also the effect of cosolvent (1-propanol) on these interactions.

Volumetric, viscometric and refractive index behaviour of dl-valine, l-isoleucine and l-proline in aqueous dimethylsulphoxide at different temperatures

Densities (p), viscosities (η) and refractive indices (n) of aqueous dimethylsulphoxide (DMSO) (10% v/v) and of solutions of amino acids [dl-valine (Val), l-isoleucine (Ile) and l-proline (Pro)] (0.01-0.05 M) in aqueous-DMSO were measured at 298.15, 303.15, 308.15 and 313.15 K. The density data have been used to calculate apparent molar volume (Φ v ), limiting partial molar volume (Φ o v ), and the slope (S v ), using Masson's equation. The viscosity data were analysed by means of Jones-Dole equation. The activation parameters of viscous flow, namely, free energies of activation per mole of solvent (μ o 1 *) and per mole of solute (μ o 2 *), respectively, were obtained by using transition state theory. The refractive index data was used to calculate molar refraction (R m ) for all the three amino acids in aqueous-DMSO solvent mixtures. All these parameters are used to study solute-solvent and solute-solute interactions in the aforementioned mixtures.

Volumetric and viscometric properties of urea and D-glucose in aqueous glycine at 308 K

Density, viscosity and refractive index data for urea and D-glucose in (0.01, 0.02 and 0.03 M) glycine + water mixed solvent as a function of urea/glucose concentration are presented at 308 K. The density data have been used to obtain limiting apparent molar volume (Φ 0 v ) and the slope (S* v ) using Masson's equation. The viscosity data are analysed by means of Jones-Dole equation. The activation parameters of viscous flow, namely free energy of activation per mole of solvent, (Δμ 0 # 1 ) and free energy of activation per mole of solute, (Δμ 0 # 2 ), were obtained by the application of transition-state theory. The refractive index was used to calculate molar refractive index, (R D ) of the solutes in different solvent mixtures. All these parameters are used to study the solute-solvent and solute-solute interactions in the mixtures used in the present investigation.

A new model for predicting activity coefficients in aqueous solutions of amino acids and peptides

A new two-parameter model based on the perturbation of a hard-sphere reference has been developed to correlate the activity coefficients of several amino acids and simple peptides in aqueous solutions. The hard-sphere equation of state used as the reference in the model was proposed recently by Ghotbi and Vera. The perturbation terms coupled with the reference hard-sphere equation of state are attributed to the dispersion forces and the dipole–dipole interactions. The Lennard-Jones and Keesom potential functions are used to represent the dispersion and dipole–dipole interactions, respectively. The results of the new model are compared with those obtained by other models. It is shown that the new model can more accurately correlate the activity coefficients of amino acids and peptides in comparison with the other available models in the literature. The model was also used to correlate the solubility of several amino acids in aqueous solutions. The results show that the model can accurately correlate the solubility of the experimental data over a wide range of temperatures with only two adjustable parameters. New values for Gibbs free energy change, Δ g, and enthalpy change, Δ h, of the solute, i.e., amino acid for transferring one mole of solute from a saturated solution to a hypothetical aqueous solution with an activity of one molal at temperature 298.15 K are also reported.

D-β-Hydroxybutyrate Reaction Kinetics Studied in Nanoliter Volumes Using a Capillary Polarimeter

A laser-based capillary polarimetric detector (CPD) has been configured to allow for the analysis of optically active molecules at physiological temperatures and within a 40 nL sample volume. In the CPD, interference fringes contained within a 360° fan of scattered light result from the interaction between a polarized laser beam and a 240 μm i.d. capillary tube. Here it is shown that these fringes change in a reproducible manner with solute optical activity, facilitating a 3σ detection limit of 1.7 × 10−3 M d-β-hydroxybutyrate corresponding to 68 × 10−12 mole (7 × 10−9 gram) of solute. Further, with the use of this improved and novel polarimeter, the noninvasive study of enzyme reaction kinetics for d-β-hydroxybutyrate (50 mg/dL) and hydroxybutyrate dehydrogenase (100 μL of 50 units/L) has been evaluated for the first time in the absence of NAD. The rate constant for this reaction was found to follow first-order kinetics and determined to be 2.2 × 10−2 s−1. The prospect of directly studying the influence of enzyme cofactors on reaction kinetics is at hand, and the observations presented suggest that the application of monitoring insulin therapy for patients experiencing ketoacidosis is a tractable problem for the CPD.

A simple model for predicting the viscosity of sugar and oligosaccharide solutions

A model originally developed to predict the viscosity of concentrated electrolyte solutions was adapted to fit viscosity data of various sugars and sugar mixtures up to very high concentrations. The model was μ r = a exp( EX ), where μ r is the relative viscosity, a and E are parameters (in most cases a was very close to unity). The model was used to describe the concentration dependence of viscosity of sucrose, fructose, glucose, maltose, lactose and corn syrup (having different dextrose equivalent values) solutions up to very high solids concentration. The molecular weight of the sugar was a main factor in determining the value of parameter E , which on theoretical grounds may be somewhat related to the free energy of activation for viscous flow per mole of solute.

Theoretical Analysis of Osmotic Agents in Peritoneal Dialysis. What Size is An Ideal Osmotic Agent?

In this article the difference between osmotic fluid flow (ultrafiltration) as driven by osmotic pressure and diffusion through thin leaky membranes is discussed. It is pointed out that water transport induced by osmosis is fundamentally different from the process of water diffusion. Applying modern hydrodynamic pore theory, the molar solute concentration and the solute concentration in grams per 100 mL, exerting the same initial transmembrane osmotic pressure as a 1% glucose solution, was investigated as a function of solute molecular weight (MW). It was then assumed, base on experimental data, that the major pathway responsible for the peritoneal osmotic barrier characteristics is represented by pores of radius approximately 47 A. With increasing solute radius, the osmotic reflection coefficient (sigma) and, hence, the osmotic efficiency per mole of solute will increase. However, simultaneously, the molar concentration per unit solute weight will decrease. The balance point between these two events apparently occurs at a solute MW of approximately 1 kDa. An additional advantage of using solutes of high MW as osmotic agents during peritoneal dialysis (PD), rather than increased osmotic efficiency per se, lies in the fact that large solutes, due to their low peritoneal diffusion capacity, will maintain a sustained rate of ultrafiltration (osmosis) over a prolonged period. To illustrate this, we have performed computer simulations of peritoneal fluid transport according to the three-pore model of peritoneal permselectivity. According to these simulations, 4% of an 800 Da polymer solution (+50 mmol/L above isotonicity) will produce the same cumulative amount of intraperitoneal fluid volume ultrafiltered (UF) during 360-400 minutes as 4% of a 2 kDa polymer solution (+20 mmol/L) or 6.5% of a 10 kDa polymer solution (+6.5 mmol/L) having the same electrolyte concentration as dialysis solutions conventionally used for PD. Similar cumulative UF volumes (during 400 minutes) can be obtained by a 2.5% glycerol (+272 mmol/L) or a 3.2% glucose-containing dialysis solution (+177 mmol/L) with conventional electrolyte composition.

Solvation of Ag + ions in some nitriles; a Fourier transform Raman spectroscopic study

Silver nitrate solutions in four nitriles (acetonitrile, benzonitrile, ethylcyanoacetate and acrylonitrile), in a range of concentration between 37 and 3 molecules of solvent per mole of solute, have been studied using Fourier transform Raman spectroscopy. The new band in the ν(CN) region arising from the coordinated species Ag +… (nitrile) n has been analysed in detail by means of deconvolution and band-fitting procedures. The wavenumber shift of the new band (about 19 cm −1) seems to be independent of the nitrile and in all the cases studied the molar scattering factors are strongly increased due to the effect of the cation. Weak solvation spheres around the silver ion are identified spectroscopically. An effect of the weak solvation is the lack of a definite and constant solvation number for the metal ion, and only numbers at infinite dilution can be obtained. These solvation numbers are two for benzonitrile and three for acrylonitrile, ethylcyanoacetate and acetonitrile. However, the solvation number obtained for acetonitrile in this work is important due to the effect of the Fermi resonance in the stretching bands used for calculations; because of this, the literature work for complexes in acetonitrile solution should be critically revised.

Heat effects for toluene adsorption on activated carbon from supercritical carbon dioxide

The isochoric adsorption isotherms of toluene from supercritical carbon dioxide on activated carbon were provided in this study. The experimental data were obtained by a recycle technique. The activated carbon pellets were loaded in a spinning basket autoclave. After injection of a certain amount of toluene into autoclave, the equilibrium loadings of toluene on activated carbon at various temperatures were measured in a path of gradually decreasing or increasing temperatures. The equilibrium adsorption data for temperatures ranging from 308 to 338 K at CO 2 densities of 0.32, 0.45, and 0.69 g cm −3 were correlated accurately by the Toth isotherm expression. A thermodynamic model was proposed herein related the mole fraction of toluene in supercritical CO 2 phase with the changes in partial molar enthalpies, partial molar volumes, and partial molar internal energies of toluene. The experimental data obtained were analyzed by the proposed model revealing that the changes in partial molar enthalpies and partial molar volumes were always positive for the conditions studied and were significantly large near the CO 2 critical condition. This enthalpy change represents the energy transfer of one mole of toluene from the nonideal, supercritical solution onto the adsorbent surface at isobaric and isothermal operations. This quantity, however, is not the heat of adsorption as conventionally defined which represents the energy transfer of one mole of solute from an ideal gas solution onto the adsorbent surface. But on the other hand, the change in partial molar internal energies of toluene was found to be always negative. This indicated that the energy effects associated with an adsorption process at supercritical conditions should be clearly defined so as to elucidate the adsorption is endothermic or exothermic.

Heats of solution of 1-nonanol, 1-decanol and 1-undecanol in cyclohexane at 298.15 K and 308.15 K

The enthalpies of solution of 1-nonanol, 1-decanol and 1-undecanol in cyclohexane were measured at 298.15 K. and 308.15 K. The experimental values of enthalpy changes per mole of solution as a function of solute mole fraction are given in the form of a second-degree polynomial. The hydrogen bond enthalpies of 1-alkanol molecules in the systems studied were obtained from the enthalpy changes per mole of solute at infinite dilution. In addition, the values of the relative molar enthalpy of the pure solutes, the relative partial molar enthalpy of the solutes and solvent, and the relative apparent molar enthalpy of the solutes were determined at 298.15 K and 308.15 K. On the basis of a semi-ideal model of associated solution, the practical molal osmotic coefficients and the molal activity coefficient of the solutes were calculated from the thermochemical data. The non-ideal behaviour of these systems was described by the excess thermodynamic functions of solution, as well as by the partial excess thermodynamic functions of solutes and solvent. The enthalpic pair interaction coefficients were determined in the sense of the McMillan-Mayer theory. The non-ideality of the investigated systems was also described on the basis of an association model with an extended series of multimers, assuming that each addition of monomer to the progressively growing oligomeric species is more difficult.

Heats of solution of 1-nonanol and 1-undecanol in n-hexane, n-heptane, n-decane and n-hexadecane at 298.15 K

The heats of mixing of 1-nonanol or 1-undecanol in n-hexane, n-heptane, n-decane and n-hexadecane were measured at 298.15 K. The enthalpy changes per mole of solution were expressed as a second degree polynomial in X, the mole fraction of solute in the concentration range studied. From the enthalpy changes per mole of solute at infinite dilution, the hydrogen-bond enthalpy of 1-alkanol molecules in the solvents investigated was determined. From thermochemical data the relative molar enthalpies of the pure solutes, the relative partial molar enthalpies of the solute and the solvent and the relative apparent molar enthalpies of the solutes were deduced. Assuming that the enthalpies of the stepwise associations are equal for both solutes in the solvents investigated, the practical osmotic coefficients were calculated from the apparent molar enthalpy of the solutes and the enthalpy of a stepwise association reaction on the basis of a semi-ideal model of associated solutions proposed by Prigogine. The molal activity coefficients of the solutes were determined via Bjerrum's relation. The non-ideal behaviour of these systems was described by the excess thermodynamic functions, i.e. the excess Gibbs free energy, excess enthalpy and excess entropy, as well as with partial molar excess Gibbs free energy of solute and solvent. Furthermore, the non-ideality of the investigated systems was treated on the basis of an association model with an extended series of multimers, supposing that the first stepwise associations occur more readily than the rest. In addition, the pair virial coefficients of the solutes were determined from the excess enthalpies of solutions according to McMillan-Mayer theory.

Thermodynamic properties of nonpolar solutes in water and the structure of hydrophobic hydration shells

Experimental partial molar entropies and heat capacities in water for noble gases, nonpolar diatomic gases, and hydrocarbons were analyzed thermodynamically by delphic dissection to evaluate the contributions from solute-induced perturbations of the water network. These contributions, which are typically large, were then interpreted in terms of the familiar two-state model of liquid water. Changes in the fractions of the two states and of their relative enthalpies, per mole of solute, were thus evaluated. The numbers of water molecules that are nearest neighbors to the solute, and the manner in which the nearest neighbors are tied to the bulk water network, could be elucidated.

Excess pressures for aqueous solutions

Gibson's concept of an excess pressure is applied to an analysis of the properties of solutions containing both salts and neutral solutes. Definitions of excess pressures are examined in terms of volumes occupied by one mole of solute and one mole of solvent in solution, and in terms of partial molar and apparent molar volumes of solute and solvent. A distinction is drawn between occupied volumes and partial molar volumes and between excess pressures which characterise solute–solvent interactions and excess pressures which include contributions from solute–solute interactions in real solutions. Descriptions of excess pressures in terms of the effect of solute on a solvent is linked to the description in terms of a structural temperature along the lines proposed by Bernal and Fowler. Excess pressures are calculated for aqueous solutions containing (a) sodium chloride, (b) tetrabutylammonium bromide, (c) urea, (d) t-butyl alcohol, (c) DMSO and (d) hydrogen peroxide.

The Size and Scattering Coefficient of Urban Aerosol Particles at Washington, DC as a Function of Relative Humidity

The relative humidity dependence of the size and scattering coefficient of atmospheric aerosol particles was measured at Washington, DC during the period 26–31 July 1979. Particle growth curves (i.e., curves of the ratio r/r0, of particle radius to particle dry radius, versus relative humidity) were calculated using measured values of the particle composition parameter B ≡ ν¯ϕεMwρ0/ρwM̄s, where ρ0 is the density of the particle in dry state, ρw and Mw the density and molecular weight of water, ε the mass fraction of soluble material in the particle. M̄s the molecular weight of the soluble material, ν¯ the mean number of moles of ions per mole of solute, and ϕ¯ the mean value of the practical osmotic coefficient. To determine B, a mobility analyzer was used to transmit dry particles of nearly uniform size to a thermal gradient diffusion cloud chamber where the supersaturation (Sc,) necessary to activate the particles was measured. Then, a relationship between Sc, r0 and B was employed to determine B. The measurements were made for particles in the size range between 0.03 and 0.08 μm radius. The value of B ranged from 0.10 to 0.40 and averaged 0.23 for the period. For B = 0.23 and r0 = 0.05 μm, the computed values of r/r0 are 1.22, 1.37, 1.57 and 1.90 at relative humidities of 80, 90, 95 and 98%, respectively. The light-scattering coefficient as a function of (decreasing) relative humidity was measured directly by controlling the relative humidity of the air flowing to an integrating nephelometer. A smooth variation of scattering coefficient with humidity was observed. On the average, the scattering coefficient changed by a factor of 3.5 between 30 and 95% relative humidity. In general, the measured dependence of the scattering coefficient on relative humidity was consistent with that computed from the particle growth curves.

Conductance‐Viscosity Studies on Some Moderately Concentrated Nonaqueous Electrolyte Solutions from −50° to 125°C: II . Solutions of ,, and in Propylene Carbonate

Matching conductance, viscosity, and density data at 25° intervals between −50° and 125°C have been determined and analyzed for moderately concentrated solutions of three quaternary ammonium halides in propylene carbonate. Detailed results are presented for the fitting of experimental data as functions of molal concentration and temperature to appropriate equations by computer least squares procedures. Calculated results related to moles of solvent displaced per mole of solute and also apparent molal volumes indicate the lack of significant ion‐solvent interactions in the solutions of the quaternary ammonium salts in propylene carbonate. Additionally, conductance‐viscosity products and activation energies of viscous flow and conductance have been calculated and discussed. Throughout the broadly varying experimental conditions over the 175°C range, the conductances of the three salts have been found to be fairly closely proportional to the fluidity, or reciprocal of the viscosity, of the medium.

Adsorption of 1-butanol and 1-pentanoic acid from the aqueous solution on polymers. Analysis of the solid—liquid interfacial activity

In order to evaluate the solid—liquid interfacial activity of surfactant, contact angles of aqueous solutions of 1—butanol and 1—pentanoic acid on polypropylene (PP), polystyrene (PSt), polyvinyl chloride (PVC), and polymethyl methacrylate (PMMA) were measured. In many cases, discontinuities in slope of the contact angle θ vs concentration x (mole fraction) curves were observed, which was attributed to the change of the adsorption state from the horizontal to the vertical one. From these data, the decrease of the solid—liquid interfacial tension Δ γSL due to adsorption of surfactant was calculated. A parameter α, defined as lim ( ΔγSL x ), was introduced which was determined by extrapolation of Δγ- x plot. x → 0 The free energy of adsorption ΔG ads 0 was calculated from α value, and ΔG ads ∗ was calculated by: ΔG ads ∗ = ΔG ads 0 - NA 0γLV 0 cos θ 0 , where the last term represents the work of immersion of polymer into water per the area NA 0 of one mole of solute. The α values (and also − ΔG ads 0) are large for PP and small for PMMA. However, −ΔG ads ∗ values are small for PP and large for PMMA, which corresponds to the stronger interaction of PMMA with surfactant than of PP due to the larger polarity of PMMA.

Magnetic Properties of Dilute Alloys of Cr, Mn, and Ni in4dand5dTransition Metals

Magnetic-susceptibility measurements between 4 and 300\ifmmode^\circ\else\textdegree\fi{}K of dilute magnetic alloys of Cr, Mn, and Ni in various $4d$ and $5d$ transition metals are reported. Mn in Mo and Rh shows a localized magnetic moment with Kondo-type behavior. Below the Kondo temperature ${T}_{K}$, the susceptibility increases, by a term proportional to ($\frac{{T}_{K}}{T}$); faster than the Curie-Weiss law. This logarithmic term seems to be common to all dilute magnetic alloys of $3d$ solutes in transition metals. In addition to a localized moment, Mn causes a large change in the temperature-independent susceptibility of the order of ${10}^{\ensuremath{-}3}$ emu per mole of solute. Similar large changes are also observed for other dilute magnetic alloys. It seems to be quite general that the occurrence of localized moment in dilute alloys is accompanied by a large increase in the temperature-independent susceptibility. These increases are too large to be understood within the present theories of localized magnetic states. Large increases in the temperature-independent susceptibility are also observed for some alloys with no localized moments. For Mn in Re, this increase corresponds to about ${10}^{\ensuremath{-}2}$ emu per mole of solute.

The disulphuric acid solvent system. Part II. Cryoscopic and conductimetric measurements on some organic and inorganic bases

Cryoscopic and conductimetric measurements on a number of weak organic bases have shown that they are more extensively ionized in disulphuric acid than in sulphuric acid or fluorosulphuric acid. It is concluded that disulphuric acid is a more acidic medium than either of these other solvents. It is shown how the cryoscopic data for any solute may be interpreted to give a value for ν, the total number of moles of all species except sulphuric acid, formed in solution by one mole of a solute, and also a value for the number of moles of sulphuric acid. The conductimetric data may be interpreted to give the number of moles of HS3O10– and H2SO4 formed by each mole of solute. The results of the conductimetric and cryoscopic measurements show that HClO4 behaves as a very weak base and that KCl and KF give quantitative formation of HSO3Cl and HSO3F respectively, both of which behave as nonelectrolytes. KlO3 forms lO2SO4H and KH2PO4 gives the P(OH)4+ ion. Nitric acid gives the nitronium ion, and triphenylmethanol the triphenylcarbonium ion. A number of carboxylic acids, are shown to be dehydrated to the corresponding acyl ion, e.g., CH3CO2H→CH3CO+.

Ionic Hydration in an Aqueous Electrolyte Solution and Its Parameter

Abstract Tait’s equation for water and Harned and Owen’s treatment of an electrolyte solution, together with sound velocity data, enabled the calculation of the molar volume of electrolytes in the solution state. The results agreed fairly well with the molar volume of the super-cooled molten electrolyte extrapolated to room temperature. The concentration coefficient of electrostrictive pressure, L=Pe/C1C2, the volume contraction due to the dissolution of one mole of solute, ΔV, and the volume of hydration water per mole of solute, Vh, as an incompressible part of water have been evaluated. We have found a common variable, [h], for L, ΔV and Vh, and it has been proposed that this variable can be used as a parameter of hydration expressing the mole number of hydration water per mole of electrolyte. A conventional hydration number, [h*], was also proposed.

Magnetic Susceptibility Measurements of Small Samples. II. Solutions

A microtechnique for measuring the magnetic susceptibility of paramagnetic compounds in solution is described. Solutions containing less than 10−8 mole of solute have been measured, which represents a sensitivity increase of more than 104 over the classical Gouy method. The method depends upon balancing magnetic forces in an inhomogeneous magnetic field against density gradients in the solution.