Potentiométrie de précision à basse température dans les mélanges eau – éthylène glycol; grandeurs thermodynamiques relatives aux ionisations de l'acide acétique et du solvant mixte

1983 ◽  
Vol 61 (10) ◽  
pp. 2344-2348 ◽  
Author(s):  
Hamed Bahri ◽  
Jean-Claude Hallé ◽  
Robert Schaal

Electromotive force measurements of cells without liquid-junction containing hydrogen electrodes and silver – silver chloride electrodes have been used to derive the dissociation constants of acetic acid and solvent water – ethylene glycol mixtures (50 and 70 mass % of ethyleneglycol) at 14 temperatures from −35 to 30 °C. Primary acidity standards related to these acetic buffered and sodium hydroxide solutions are given.


2019 ◽  
Vol 7 (1) ◽  
pp. 18-26
Author(s):  
Soleen S. Ahmed ◽  
Lazgin A. Jamil

The first and second dissociation constants of malonic acid in different composition of (ethylene glycol-water)%, (10, 20 and 30)% mixed solvent determined using the electromotive force measurements of galvanic cells without liquid junction at nine different temperatures,  at  interval, including the body temperature. The value of the first and second thermodynamic dissociation constants have been used to determine the thermodynamic quantities of two dissociation processes. These quantities involved the standard free energy,  standard enthalpy change,  standard entropy change,  and standard heat capacity change.



1980 ◽  
Vol 58 (4) ◽  
pp. 323-327 ◽  
Author(s):  
Upendra Nath Dash ◽  
Uttam Kumar Nayak

The ionization constant, K, of trans-crotonic acid, and the first and second ionization constants, K1 and K2, of adipic acid have been determined in water at seven different temperatures ranging from 15 to 45 °C with the help of the cells without liquid junction using silver – silver chloride and quinhydrone electrodes. The variations of pK, pK1, and pK2 with temperature have been expressed by the equations[Formula: see text]and[Formula: see text]From the temperature coefficient of the ionization constants, the standard enthalpy, entropy, Gibbs energy, and heat capacity changes of the corresponding dissociation processes have been calculated. Using the values of ionization constants of adipic acid, the standard potential of the Ag(s)/Ag2Ad(s)/Ad2− electrode, and the related standard thermodynamic quantities for the electrode process[Formula: see text]have been calculated in water at those temperatures.



1975 ◽  
Vol 28 (4) ◽  
pp. 793 ◽  
Author(s):  
UN Dash ◽  
B Nayak

The first and second ionization constants of phthalic acid have been determined, in formamide, at temperatures ranging from 5� to 45�C at 5� intervals, with the help of cells without liquid junction using quinhydrone and silver-silver chloride electrodes. By means of the Bjerrum equation, the distance r between the acidic groups has been estimated in formamide at different temperatures.



1973 ◽  
Vol 26 (1) ◽  
pp. 115 ◽  
Author(s):  
B Nayak ◽  
UN Dash

The first and the second ionization constants of phthalic acid have been determined, in formamide, at 25� with the help of cells without liquid junction using quinhydrone and silver-silver chloride electrodes. The values of pK1a and pK2a were found to be 4.214�0.02 and 7.716�0.01, respectively, at this temperature.



1930 ◽  
Vol 14 (1) ◽  
pp. 99-103 ◽  
Author(s):  
David I. Hitchcock

Electromotive force measurements of cells without liquid junction, of the type Ag, AgCl, HCl + protein, H2, lead to the conclusion that 1 gm. of edestin (or, more probably, edestan) combines with a maximum of 13.4 x 10–4 equivalents of H+ and 3.9 x 10–4 equivalents of Cl-, when the protein is dissolved in 0.1 M HCl.



1957 ◽  
Vol 35 (11) ◽  
pp. 1254-1259 ◽  
Author(s):  
S. N. Flengas ◽  
T. R. Ingraham

Using a reversible silver – silver chloride reference electrode, described in the first paper of this series, standard electrode potentials have been established for the systems lead – lead chloride, zinc – zinc chloride, and nickel – nickelous chloride, in melts containing equimolar quantities of KCl and NaCl. Deviations from ideality were observed, and these were attributed to the formation of complexes. Dissociation constants for the complexes were calculated. The effect of temperature on the electromotive forces of the voltaic cells was also measured, and the heats of the cell reactions were calculated from the data.



1957 ◽  
Vol 35 (10) ◽  
pp. 1139-1149 ◽  
Author(s):  
S. N. Flengas ◽  
T. R. Ingraham

A reversible silver − silver chloride reference electrode for use in melts at high temperatures has been developed. It was found that the solution of silver chloride in an equimolar mixture of KCl–NaCl melt is ideal for the range of concentrations studied, i.e. 1.0 × 10−3 to 6.0 × 10−2 mole fraction of AgCl.The electromotive force of the voltaic cell[Formula: see text]in which the half-cell to the right contains the above-mentioned reference electrode, was measured as a function of CoCl2 concentration. The applicability of the Nernst equation to this system was established. Deviation from ideality was observed in the case of the solution of CoCl2 in the melt solvent, and this was attributed to the formation of a complex. The dissociation constant of this complex was calculated as 4.50 × 10−2 at 710 °C.The effect of temperature on the electromotive force of this cell was also measured, and the heat of the cell reaction in the presence of solvent (Co + 2AgCl → CoCl2 + 2Ag) was calculated from the data as 22.8 ± 1.3 kcal.The thermodynamic significance of the standard electrode potential of the Co–Ag voltaic cell, derived experimentally as 0.324 volt, is discussed briefly.



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