Electromotive force measurements

G. Scatchard and R. F. Tefft, "Electromotive Force Measurements on Cells Containing Zinc Chloride. The Activity Coefficients of the Chlorides of the Bivalent Metals", J. Am. Chem. 

Shedlovsky et al. studied mixtures of sodium decyl, dodecyl, and tetradecyl sulfates by electromotive force measurements and determined the extent of the dissociation of the sodium counterions by the micelles. From the data obtained strong interaction below the CMC was found for all of the mixtures except those containing more than 25 mol % of sodium decyl sulfate [122]. Commercial alcohol sulfates are mixtures of homologs with different hydrocarbon chains. It has been demonstrated [123] that the CMC of such products is lower than that expected by calculation from the linear relationship between log CMC and the number of carbon atoms of the alcohol as stated in Eq. (11). These results are shown in Fig. 9. 

H. Kohler and W. Gopel, Catalysis of the oxygen reduction on W18O49 electrodes by OH induced surface-states— A study based on XPS UPS and electromotive-force measurements,... 

The defect scheme shown in equation 4.68 was later confirmed by electromotive force measurements with galvanic cells (Simons, 1986) and by diffusivity mea-... 

Determination of pH values may be done either by electromotive force measurements, by colormetric methods (indicator papers, or indicator solutions), or by the glass electrode method... 

At resonance, the magnetization vector M precesses about the vector B, i of the alternating field according to eq. (1.34). As a result, a component of transverse magnetization My.j rotates in the x y plane at the Larmor frequency v0. If a receiver coil is placed in the x y plane, the rotating magnetic vector Myj induces an electromotive force measurable as an inductance current. This process is called nuclear induction [5, 8]. The orientation of the coil axis will affect the phase relative to B1 i but not the magnitude of the induction current. 

PbCl2 NH4C1 (c). Bronsted8 determined, from electromotive force measurements, the heat of formation of this substance from solid lead chloride and solid ammonium chloride to be 0.35. 

Electromotive force measured with electrodes and is proportional to flow rate... 

Inman D., The Electrode-Melt Interface at High Temperature in Electromotive Force Measurements in High-Temperature Systems, Proc. Symp. Nuffield Research Group, Imperial College, London, 1968, p. 163. 

THE CHEMICAL ACTIVITY OF THE IONS OF HYDROCHLORIC ACID DETERMINED BY ELECTROMOTIVE FORCE MEASUREMENTS... 

Electromotive force measurements of HC1 solutions in pure NMA and in NMA/dioxane solvent mixtures using the silver-silver chloride electrode have been reported by Dawson and his co-workers (1,2,3). The only other potentiometric studies in a solvent of dielectric constant higher than that of water appear to have been in formamide (6,7,8,9, 10) and in N-methylpropionamide (NMP) (11,12,13,14,15). 

Electromotive force measurements of the cell Pt, H2 HBr(m), X% alcohol, Y% water AgBr-Ag were made at 25°, 35°, and 45°C in the following solvent systems (1) water, (2) water-ethanol (30%, 60%, 90%, 99% ethanol), (3) anhydrous ethanol, (4) water-tert-butanol (30%, 60%, 91% and 99% tert-butanol), and (5) anhydrous tert-butanol. Calculations of standard cell potential were made using the Debye-Huckel theory as extended by Gronwall, LaMer, and Sandved. Gibbs free energy, enthalpy, entropy changes, and mean ionic activity coefficients were calculated for each solvent mixture and temperature. Relationships of the stand-ard potentials and thermodynamic functons with respect to solvent compositions in the two mixed-solvent systems and the pure solvents were discussed. 

Table I. Electromotive Force Measurements of the Galvanic Cell Containing Hydrobromic Acid in Ethanol—Water and tert-Butanol—Water Solvents, and in the Separate Solvent Components...

Saboungi, Marie Louise Marr, Jane Blander, Milton. "Thermodynamic Properties of a Quasi-ionic Alloy From Electromotive Force Measurements The Li-Pb System," J. of Chem. Phys. 1978. 

Barbi, G.B., 1964, Thermodynamic functions and phase stability limits by electromotive force measurements on solid electrolytic cells. J. Phys. Chem., 68 1025-1029. 

Three methods have been generally employed for the experimental determination of transference numbers the first, based on the procedure originally proposed by Hittorf (1853), involves measurement of changes of concentration in the vicinity of the electrodes in the second, known as the moving boundary method, the rate of motion of the boundary between two solutions under the influence of current is studied (cf. p. 116) the third method, which will be considered in Chap. VI, is based on electromotive force measurements of suitable cells. 

The experimentally determined activity coefficients, based on vapor pressure, freezing-point and electromotive force measurements, for a number of typical electrolytes of different valence types in aqueous solution at 25 , are represented in Fig. 49, in which the values of log / are plotted against the square-root of the ionic strength in these cases the solutions contained no other electrolyte than the one under consideration. Since the Debye-Htickel constant A for water at 25 is seen from Table XXXV to be 0.509, the limiting slopes of the plots in Fig. 49 should be equal to —0.509 the results to be expected theoretically, calculated in this manner, are shown by the dotted lines. It is evident that the experimental results approach the values required by the Debye-Hiickel limiting law as infinite dilution is attained. The influence of valence on the dependence of the activity coefficient on concentration is evidently in agreement with theoretical expectation. Another verification of the valence factor in the Debye-Hiickel equation will be given later (p. 177). 

Elimination of Liquid Junction Potentials.—Electromotive force measurements are frequently used to determine thermodynamic quantities of various kinds in this connection the tendency in recent years has been to employ, as far as possible, cells without transference, so as to avoid liquid junctions, or, in certain ca.ses, cells in w hich a junction is formed between two solutions of the same electrolyte. As explained above, the potential of the latter type of junction is, within reasonable limits, independent of the method of forming the boundary. 

Funasaki, N. Kawaguchi, R. Ishikawa, S. Hada, S. Neya, S. Katsu, T. Quantitative estimation of the bitter taste intensity of oxyphenonium bromide reduced by cyclodextrins from electromotive force measurements. Anal. Chem. 1999, 71 (9), 1733-1736. 

Values of the mean ion activity coefficient may be determined experimentally using several methods, including electromotive force measurement, solubility determinations and colligative properties. It is possible, however, to calculate y+ in very dilute solution... 

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