Osmotic coefficients and activity coefficients of aqueous mixtures of sodium chloride and sodium carbonate at 25°C

1980 ◽  
Vol 33 (9) ◽  
pp. 1903 ◽  
Author(s):  
Jr DR White ◽  
RG Bates
Keyword(s):  
Sodium Chloride ◽  
Activity Coefficients ◽  
Sodium Carbonate ◽  
Osmotic Coefficients ◽  
Pitzer Equation ◽  
Aqueous Mixtures ◽  
Free Energies ◽  
Scatchard Equation ◽  
The Individual ◽  
Reference Electrolyte

Isopiestic vapour-pressure measurements have been used to determine the osmotic coefficients of aqueous mixtures of sodium chloride and sodium carbonate at 25°C. Solutions of sodium chloride were used as the reference electrolyte. The data served to evaluate the excess free energies of mixing as well as the mixing parameters of the Scatchard and Pitzer theories. The three-parameter form of the Scatchard equation accounts well for the experimental results, and the Pitzer equation with two adjustable parameters does equally well. The activity coefficients of the individual salts in the mixtures have been calculated.

Activity coefficients of NaCl in NaCl–NaOAc–H2O at 25, 35, and 45 °C

1991 ◽  
Vol 69 (1) ◽  
pp. 111-115 ◽  
Author(s):  
S. Manohar ◽  
J. Ananthaswamy
Keyword(s):  
Sodium Chloride ◽  
Key Words ◽  
Activity Coefficients ◽  
Sodium Acetate ◽  
Osmotic Coefficients ◽  
Free Energies ◽  
Harned's Rule ◽  
Pitzer Formalism ◽  
Scatchard Equation

The activity coefficients of NaCl were estimated by measuring the EMFs of the cell[Formula: see text]at four ionic strengths, i.e., 0.5, 1.0, 2.0, and 3.0 mol/kg and at temperatures 25, 35, and 45 °C. The results were analyzed in terms of Harned's rule, the Pitzer and Rush–Johnson–Scatchard treatments. Osmotic coefficients and excess free energies of mixing were calculated at all ionic strengths and temperatures studied. Key words: activity coefficients, sodium chloride, sodium acetate, Pitzer formalism, Scatchard equation.

Free energies and entropies of transfer of hydrogen halides from water to aqueous 2-methoxy ethanol and structuredness of the solvents

1985 ◽  
Vol 63 (4) ◽  
pp. 798-803 ◽  
Author(s):  
Prabir K. Guha ◽  
Kiron K. Kundu
Keyword(s):  
Dielectric Constant ◽  
Mixed Solvents ◽  
Three Dimensional ◽  
Halide Ions ◽  
Aqueous Mixtures ◽  
Free Energies ◽  
Hydrogen Halides ◽  
Emf Measurements ◽  
Composition Profiles ◽  
The Individual

Standard free energies (ΔGt0) and entropies (ΔSt0) of transfer of HBr and HI from water to some aqueous solutions of 2-methoxy ethanol (ME) have been determined from emf measurements of the cells: Pt, H2 (g, 1 atm)/HBr (m), solvent/AgBr–Ag and Pt, H2 (g, 1 atm)/KOH (m1), KI (m2), solvent/AgI–Ag, respectively, at seven equidistant temperatures ranging from 15 to 45 °C. ΔGt0 values of HBr and HI as well as of HCl obtained from literature, and particularly that of the individual ions obtained by tetraphenylarsonium tetraphenylboron (TATB) assumption, suggest that while H+ is increasingly stabilized by cosolvent-induced larger "basicity", halide ions (X−) are increasingly destabilized by cosolvent-induced decreased "acidity" and the dielectric constant of the mixed solvents compared to that of water. Analysis of the variation of the observed TΔSt0(HX) and particularly of ΔY (= TΔSt0(H+) + TΔS0t.ch (X−), with composition, in the light of Kundu etal's semi-quantitative theory reveals that ME induces breakdown of three dimensional (3D) tetrahedral structures of water at water-rich compositions. This is being followed by an ordered region due to possible H-bonded cosolvent–water complexation and then the usual disordered region due to packing imbalance. Comparison of ΔY(HI)–composition profiles for aqueous mixtures of t-butanol (ButOH), ethylene glycol (EG), and 1,2-dimethoxy ethane (DME) also demonstrates that the remarkable enhancement of 3D water structures by the well known structure promoter ButOH gets succintly diminished when cosolvent ButOH is replaced by EG, ME, and DME, as is expected from structural and electronic considerations of the cosolvents.

Solvent effect on the dissociation of p-nitroanilinium ion in glycerol–water media at 25 °C

1984 ◽  
Vol 62 (11) ◽  
pp. 2245-2248
Author(s):  
Amrita Lal De ◽  
Tapas Kumar De
Keyword(s):  
Solvent Effect ◽  
Dissociation Constants ◽  
Mixed Solvents ◽  
Individual Species ◽  
Aqueous Mixtures ◽  
Free Energies ◽  
Monohydric Alcohol ◽  
Glycerol Water ◽  
Alcohol Water ◽  
The Individual

Thermodynamic dissociation constants (sK) of p-nitroanilinium ion (BH+) have been determined at 25 °C in aqueous mixtures of 10, 30, 50, 70, and 90 wt.% of glycerol (GL) by spectrophotometric measurements. Standard free energies, [Formula: see text], of p-nitroaniline (B) from water to mixed solvents have been evaluated from the measurement of solubilities at 25 °C. p(sK) values decrease with increase in mol% of GL and pass through a minimum and then increase very slowly. The solvent effect on the dissociation, δ(ΔG0) = 2.303RT [p(sK)N – p(wK)N] has been discussed in terms of the standard free energies of transfer [Formula: see text] from water to aqueous mixtures of GL of the uncharged base (B), the hydrochloride of the base (BHCl), hydrochloric acid (HCl), and also in terms of the individual species involved in the dissociation process. The solvent effect in trihydric alcohol – water (GL + H2O) system has been compared with those in dihydric alcohol – water (ethylene glycol + water) and monohydric alcohol – water (ethanol + water) systems available from literature. The much less solvent effect in GL + H2O has been primarily attributed to the contrasting nature of interaction of H+ and of partially charged H atoms of—NH3+ group in BH+ compared to those in other two solvent systems.

Transfer free energies of alkali metal chlorides and of some individual ions in glycerol and water mixtures

1980 ◽  
Vol 58 (1) ◽  
pp. 79-85 ◽  
Author(s):  
Indra N. Basumullick ◽  
Kiron K. Kundu
Keyword(s):  
Alkali Metal ◽  
Aqueous Mixtures ◽  
Free Energies ◽  
Dispersion Interactions ◽  
Native Conformation ◽  
Alkali Metal Chlorides ◽  
Metal Chlorides ◽  
Emf Measurements ◽  
Reference Electrolyte ◽  
Electrolyte Ph

Staqndard free energies of transfer, ΔGt0, of alkali metal chlorides from water to aqueous mixtures of 10, 30, 50, and 70 wt.% glycerol have been determined from emf measurements of the double cell comprising Ag– AgCl and K(Hg) electrodes at 25°C. These values were divided into individual ion contributions by use of tetraphenyl arsonium tetraphenyl boride (Ph4AsBPh4) assumption, the required ΔGt0 values of the reference electrolyte (Ph4AsPh4B), obtained by measuring solubilities of KBPh4, Ph4AsPi, and KPi (Pi = picrate) in the solvents. The solvation behaviour of the involved ions, as dictated by their respective ΔGt0(i) values, in this as well as in systems of other similar co-solvents like ethanol, ethylene glycol, and urea, suggests that it is determined by one or several effects of acid-base, Born-type, and dispersion interactions. Moreover, comparable stability of PH4B–, particularly in aqueous glycerol and urea, suggests that "specific interactions" are possibly responsible for the well_known folding-unfolding phenomenon of native conformation of proteins in presence of co-solvents.

The activity coefficients of elctrolytes with particular reference to aqueous mixtures of 2:2 With 1:1 electrolytes

1971 ◽  
Vol 321 (1547) ◽  
pp. 515-543 ◽  
Keyword(s):  
Exact Solution ◽  
Activity Coefficients ◽  
Infinite Dilution ◽  
Osmotic Coefficients ◽  
Ion Association ◽  
Aqueous Mixtures ◽  
General Application ◽  
Poisson Boltzmann ◽  
High Concentrations ◽  
Charged Ions

Müller’s method for the exact solution of the Poisson-Boltzm an equation (P.B.M.) has been used to produce tables for general application, for the potential, for the activity coefficients and for the osmotic coefficients of 2:2 electrolytes in aqueous solutions, both alone and in the presence of strong 1:1 electrolyte. The activity coefficients for 2:2 electrolytes were found to be equivalent to those derived by Bjerrum ’s method of ionic association up to values of s/a = z 2 e 2 / ϵkTa of about 9. Beyond this value the Poisson-Boltzmann-Müller values of the activity coefficients are significantly higher (about 10% at s/a = 11) and it is shown that the Bjerrum method is better in this range. The P.B.M. calculations show that in the presence of 1:1 electrolyte the Bjerrum treatment of ion association does not give a constant dissociation constant for a 2:2 electrolyte—even at infinite dilution of the latter—and this makes the Bjerrum method less useful when dealing with mixtures of 2:2 and 1:1 electrolytes. The P.B.M. method has been applied to the activity coefficients at CaSO 4 in NaCl solutions (up to 6 mol/1 strength) in the temperature range from 0 to 95 °C ( s/a from 7.85 to 9.05). The results shows very clearly the advantage of using the Kirkwood-Glueckauf approximation rather than the Debye-Hückel term (both in combination with the Müller extension term) when dealing with highly charged ions in solutions of high concentrations.

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