The Ionization Constant of Acetic Acid in Water–Methanol Mixtures at 25° from Conductance Measurements.

Shedlovsky, Theodore; Kay, Robert L.

doi:10.1021/j150536a003

Cited by 179 publications

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“…The free energy change caused by the variation of the standard state in each solution, which is (15) since the activity of water in aqueous solution is defined to be unity. …”

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confidence: 99%

Ionic Equilibria in Mixed Solvents. IV. Solvent Effect on Dissociation Constants of Acids

Ohtaki¹

1969

Bulletin of the Chemical Society of Japan

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Equilibrium of hydronium ions with alkoxonium ions in water-alcohol mixtures being taken into account, solvent effects on dissociation constants of acids were quantitatively interpreted by the following: free energy changes on transferring ions from an aqueous solution to a mixed solvent and difference in standard states in different solvent compositions. Choosing suitable values for effective ionic radii for ions involved, satisfactory agreements were found between experimental and calculated values of ΔpK, the difference of pK in water and in an aqueous mixture, for positively charged acids (e.g., ammonium, anilinium, etc.) as well as neutral acids yielding a negatively charged conjugate base (e. g., acetic acid, benzoic acid, p-nitrophenol, etc.).

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“…The free energy change caused by the variation of the standard state in each solution, which is (15) since the activity of water in aqueous solution is defined to be unity. …”

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confidence: 99%

Ionic Equilibria in Mixed Solvents. IV. Solvent Effect on Dissociation Constants of Acids

Ohtaki¹

1969

Bulletin of the Chemical Society of Japan

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“…K A is the association constant, (C) is the concentration of metal cation at the chosen points in the relation between (Λ) and, (γ ± ) is the mean act ivity coefficients estimated fro m the Debye Hückel limiting law as modified by Robinson and Stockes, (ε) is the dielectric of the solvents,(η 0 ) is the viscosity of the solvents, (S) is the Onsager coefficient and finally (α) is the degree of dissociation (6,7) (Tables 5-8). The physical parameters like d ielectric constant (ε) and viscosity (η 0 ) and refract ive indices (n d ) fo r pure solvents and their mixtures at different temperatures wh ich used in the analysis of the conductance data were taken from Tables (1)-(3).…”

Section: Fuoss -Shedl Ovsky Methodsmentioning

confidence: 99%

“…The values of d issociation constant (K D ), the triple ion association constant (K 3 ) [2,6,7] were calculated and recorded in tables (5)(6)(7)(8)(9)(10)(11)(12).…”

Section: Fuoss-kraus Methodsmentioning

confidence: 99%

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Electrochemical Studies on the Interaction of Cadmium Ion with Kryptofix 22 in MeOH-DMF Solutions at different Temperatures

Gomaa¹,

Al-Jahdali²

2012

SCIT

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The interaction between Cd 2+ ion and Kryptofix 22 in pure MeOH and DMF solvents and their binary mixtures (0-100 % MeOH-DMF) at different temperatures (298.15-313.15) were measured by conductometric t itrations. The conductance data in all cases were analysed using the Fuoss -Shedlovsky and Fuoss-Kraus methods to get the limiting molar conductance (Λ 0  and the association constant (K A ) simu ltaneously. Accordingly, the co mputer program of Fuoss equation has been used. The conductance studies indicate the formation of 1:1 co mplex between the Cd 2+ ion and Kryptofix 22. Fro m the conductivity data obtained, the values of the Walden products (Λ o η o ) were also calculated. Based on the composition dependence of Walden products, the influence of the solvent composition on the solvation of the ion has been discussed. Thermodynamic parameters as well as refractive indices have been determined for Cd 2+ ion in the mixed solvents at different temperatures with respect to solute-solvent interaction. This work gives a lot of data for cadmiu m ions which help in analysis.

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“…The widest Py' was attained with TOA+•TBCF3PhB The final rise and final descent were attributed to be the transfer of Li+ from FA to NX and TOA+ from NX to FA, respectively, using various concentrations of Li2SO4 or TOA+ TBCF3PhB-. TOM TBCF3PhB-dissociates fairly well in NX and the ion-pair formation constant between TOA+ and TBCF3PhB-in NX was estimated to be 81 according to Shedlovsky and Kay method [8] using the limiting equivalent conductance. The PW was also investigated at the interface of W containing 0.1 M MgSO4 and NX containing 0.05 M CV+ TPhB, TPhAs~•DPA-, EV+ TPhB-TOA+•TPhB TOA+•TDC1PhB-or TOA+ TBCF3PhB-as shown in curves a to!…”

Section: Supporting Electrolytes In Fa and Nxmentioning

confidence: 99%

The Ion Transfer From Aqueous(w), Formamide(fa) or W-Fa Mixtures to Organic Solution Studied by Polarography at the Electrolyte Solution Dropping Electrode

et al. 1991

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Formamide or aqueous-formamide mixture is introduced for the ion transfer voltammetry at a liquid/liquid interface as one phase in place of the aqueous phase. The transfer of I-, BF4-, C104-and CH3(CH2)~(CH3)3N+ (n>_1) was investigated at the interface of aqueous, formamide or the aqueousformamide mixtures and 2-nitro-m-xylene.The transfer of these ions was confirmed to be polarographically reversible. The relations are discussed between the standard Gibbs transfer free energy, L\G°~•, of these ions and the nature of the transferring ions or the properties of solvents based on the halfwave potentials in the polarograms. The AG°a of small anions from formamide to nitroxylene are smaller than those from aqueous. The effect of the addition of CH2 in CH3(CH2)n(CH3)3N+ on AG°~ from formamide to nitroxylene is smaller than that from aqueous.Key words formamide, aqueous-formamide mixture, ion transfer polarography at a liquid/liquid interface Formamide (FA) is a liquid at ordinary temperature in spite of its small molecular weight and has a large dielectric constant (e), dipole moment (it), donor number (DN) and acceptor number (AN). Since FA is a good solvent for inorganic salts, a structured solvent through hydrogen bonding and immiscible with some organic solvents of low [1], FA has been considered to be a solvent which resembles closely to water (W). In detail, however, considerable differences exist between properties of FA and W, which may reflect on the solute-solvent interaction of an ion in the solvents. If we use FA or W-FA as solvents instead of W taking into account the differences, new fields will be developed for the recognition of ions or molecules.In the present paper, the applicability of the ion transfer voltammetry [2] at the interface between FA or W-FA mixture and organic solution (Org) is demonstrated, and the ion-solvent interactions in W, FA and W-FA mixture are discussed based on the results obtained by the ion transfer polarography. EXPERIMENTAL Polarographic measurementThe polarographic cell, potentiostat, galvanostat, function generator, X-Y recorder, and the apparatus for JR drop compensation employed in the present work were identical to those described in the previous paper on the ion transfer at the W/ Org interface [3]. In recording the polarograms, W, FA or W-FA mixture containing 0.1 M Li2SO4 as the supporting electrolyte (SE) was forced upward or downward dropwise into Org containing various salts as SE through a capillary made of Teflon fluororesin. The objective ion was added into W, FA, or W-FA mixture. The mean flow rate of W, FA or W-FA mixture were 0.02 -0.05 ml s-l, and the drop-time were 3 -6 s, at open circuit. Current-scan polarograms were recorded scanning the applied current at a rate of 0.5 µA s-1 with the aid of two silver/silver chloride electrodes, SSE, and measuring the potential difference, AV, between W, FA or W-FA mixture and Org using SSE and a tetraphenylborate, TPhB-, ion selective electrode, TPhBE [3]. Here, w containing 1 M LiCI was used as the electr...

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The Ionization Constant of Acetic Acid in Water–Methanol Mixtures at 25° from Conductance Measurements.

Cited by 179 publications

References 0 publications

Ionic Equilibria in Mixed Solvents. IV. Solvent Effect on Dissociation Constants of Acids

Ionic Equilibria in Mixed Solvents. IV. Solvent Effect on Dissociation Constants of Acids

Electrochemical Studies on the Interaction of Cadmium Ion with Kryptofix 22 in MeOH-DMF Solutions at different Temperatures

The Ion Transfer From Aqueous(w), Formamide(fa) or W-Fa Mixtures to Organic Solution Studied by Polarography at the Electrolyte Solution Dropping Electrode

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