A New Method for the Estimation of Transfer Activity Coefficients of Ions From the E.M.F. of Cells With Liquid Junction

1988 ◽  
Vol 41 (10) ◽  
pp. 1523 ◽  
Author(s):  
A Berne ◽  
O Popovych
Keyword(s):  
Concentration Dependence ◽  
Activity Coefficients ◽  
Salt Bridge ◽  
Liquid Junction ◽  
Transfer Activity ◽  
Liquid Junction Potentials ◽  
Solvent Component ◽  
Calculated Liquid ◽  
Dipolar Aprotic Solvents ◽  
Junction Potential

Transfer activity coefficients of the tetraalkylammonium ions, logmγR, where R+ = Me4N+, Et4N+, Pr4N+ and Bu4N+, and of the picrate ion, logmγPic, between pairs of dipolar aprotic solvents, S1 → S2, were evaluated by combining the e.m.f . of cells Ag(cryst.)|AgClO4|RX|AgClO4|Ag( cryst .)�������������������������������� S1 ������ S2with the calculated liquid-junction potentials, Ej. The salt-bridge electrolyte RX was RClO4 and R Pic for the determinations of logmγR and logmγPic, respectively, and the solvents were: acetonitrile ( MeCN ), N,N- dimethylformamide (HCONMe2), dimethyl sulfoxide (Me2SO) and propylene carbonate ( pcar ). The logmγR values showed a systematic variation with the AgClO4 concentration, apparently caused by the concentration dependence of the solvent component of the liquid-junction potential, Ej,s, neglected in the calculations. However, the above concentration dependence was virtually eliminated from the values of logmγPic when they were calculated with the aid of our concentration-dependent logmγR data. For a number of our cells it was possible to evaluate the Ej,s, with the aid of literature data. The solvent component of Ej was found to be appreciable and varied both with the AgClO4 and the RX concentration. The Ej,s, was particularly large for cells containing pcar , with a maximum of -172 mV for the pcar | MeCN junction.

Estimation of transfer activity coefficients for single ions between dipolar aprotic solvents from the E.M.F. of cells with liquid junction

1983 ◽  
Vol 36 (9) ◽  
pp. 1767 ◽  
Author(s):  
SS Goldberg ◽  
O Popovych
Keyword(s):  
Activity Coefficients ◽  
Salt Bridge ◽  
Aprotic Solvents ◽  
Liquid Junction ◽  
Transfer Activity ◽  
Novel Method ◽  
Glass Electrodes ◽  
Tetraethylammonium Perchlorate ◽  
Dipolar Aprotic Solvents ◽  
Junction Potential

Transfer activity coefficients for the sodium ion, logmγNa, between pairs of dipolar aprotic solvents were estimated from the e.m.f. of cells consisting of two sodium-selective electrodes in different solvents connected by a salt-bridge of triisoamylbutylammonium tetraphenylborate [(tab+)BPh4-], or tetraethylammonium picrate (Et4NPic), or tetraethylammonium perchlorate (Et4NclO4). The solvents were: acetonitrile (MeCN), N,N-dimethylformamide (HCONMe2), dimethyl sulfoxide (Me2SO), propylene carbonate (pcar), and N-methylformamide (HCONHMe). Values of logmγNA were estimated first by neglecting the liquid-junction potential E, and then, for some systems, by applying an Ej correction from theory. A novel method of estimating transfer activity coefficients for single ions, based on the Ej equation, was demonstrated on the (tab+) and Pic-ions. Transfer activity coefficients for the hydrogen ion between MeCN and HCONMe2 as well as MeCN and Me2SO were similarly estimated from the e.m.f. of two pH (glass) electrodes immersed in buffer media in the above pairs of solvents.

Comparison of the free energy of transfer of electrolytes, measured with cells without transference, with the sum of the free energies of the corresponding cations and anions with the Owen-cell on standard conditions

1983 ◽  
Vol 36 (10) ◽  
pp. 1997 ◽  
Author(s):  
K Schwabe ◽  
W Hoffmann ◽  
C Queck
Keyword(s):  
Free Energy ◽  
Free Energies ◽  
Liquid Junction Potential ◽  
Liquid Junction ◽  
Ph Values ◽  
Liquid Junction Potentials ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer ◽  
Very High ◽  
Junction Potential

The comparison of S2ΔS1G°tr(E1) with the sum of the values for the corresponding cation and anion S2ΔS1G°tr(Ct+)~S2ΔS1G°tr(X-) (measured) with Owen cells, gained by double extrapolation and by the assumption that the liquid junction potential at 1→0 may be neglected) gives values which differ by not more than ±5%. Most of the investigated acids allow the conclusion that the pH values, measured in cells with transference, and having the same electrodes, give good information on the acidity of the organic solvent and its water mixtures, referred to the standard state in water. That means that the pH, changed to the same H+ concentration in the solvent compared with that in water, is essentially an effect of the free energy of transfer of the hydrogen ion and not of very high liquid junction potentials.

Transfer activity coefficients between some dipolar aprotic solvents and alcohols of salts composed of various anions and potassium complexed with Bis(4,4'(5')-t-butylbenzo)-18-crown-6

1983 ◽  
Vol 36 (9) ◽  
pp. 1753 ◽  
Author(s):  
Jr MK Chantooni ◽  
IM Kolthoff ◽  
G Roland
Keyword(s):  
Dimethyl Sulfoxide ◽  
Stability Constants ◽  
Propylene Carbonate ◽  
Activity Coefficients ◽  
Isopropyl Alcohol ◽  
The Other ◽  
Aprotic Solvents ◽  
Transfer Activity ◽  
Dipolar Aprotic Solvents

Stability constants, Kf(LK+) and Kf(LKX) = [LKX]/[L][KX] at 25� in the dipolar aprotic solvents acetone (Me2CO), acetonitrile (MeCN), propylene carbonate (pc), N,N-dimethylformamide (HCONMe2), dimethyl sulfoxide (Me2SO), as well as in the alcohols, methanol (MeOH), isopropyl alcohol (Pr1OH), and butan -1-ol (BuOH) have been determined, L being bis(4,4'(5')-t-buty1benzo)-18- crown-6 (di(BuBo)-18-cr-6). This crown is considerably more lipophylic than is dibenzo-18-crown-6. Values of Kf(LKX) have been found from values of Kf(LK+), KA(KX) and KA(LKX). Transfer activity coefficients, Me2COγS, have been calculated (based on the Parker proposal that γ(Ph4As+) = γ(BPh4-) between acetone and the various solvents used of K+, Br-, ClO4-, P1- (picrate), LK+, KX, and LKX. It is found that K+ is more strongly solvated in Me2CO than in the other aprotic solvents of low donicity. The reverse is true between Me2CO and HCONMe2 or Me2SO (even after correcting for the Born effect).

Liquid-junction potentials in ethylenediamine: Attempted calculations and evaluations using concentration cells

1977 ◽  
Vol 55 (16) ◽  
pp. 2962-2965 ◽  
Author(s):  
Suraj P. Makhija
Keyword(s):  
Sodium Iodide ◽  
Calculated Data ◽  
Potassium Bromide ◽  
Liquid Junction Potential ◽  
Liquid Junction ◽  
Sodium Amalgam ◽  
Liquid Junction Potentials ◽  
Ionic Mobilities ◽  
Concentration Cells ◽  
Junction Potential

Concentration cells of the type M(Hg)|MX(1)||MX(2)|M(Hg), where M(Hg) is potassium amalgam or sodium amalgam, were investigated with three electrolytes, potassium bromide, potassium iodide, and sodium iodide. An attempt was made to determine the necessity and magnitude of liquid-junction potential corrections. Only in the case of sodium iodide are the ionic mobilities of cation and anion quite different in ethylenediamine, and liquid-junction potential corrections are necessary to obtain agreement between observed and calculated data. The limiting equations of Nernst and of Lewis and Sargent were found to be appropriate for calculating liquid-junction potentials in ethylenediamine, provided that calculated activities were used in these equations.

Potentiometric measurements of ionized calcium in anaerobic whole blood, plasma, and serum evaluated.

1985 ◽  
Vol 31 (6) ◽  
pp. 856-860 ◽  
Author(s):  
J Wandrup ◽  
J Kvetny
Keyword(s):  
Whole Blood ◽  
Volume Fraction ◽  
Salt Bridge ◽  
Sodium Formate ◽  
Ionized Calcium ◽  
Liquid Junction ◽  
Paired Samples ◽  
Significant Difference ◽  
Junction Potential ◽  
Venous Plasma

Abstract The measurements of ionized calcium and pH in paired samples of anaerobic capillary whole blood, venous whole blood, venous plasma, and venous serum have been evaluated with a modified ICA 1 analyzer and compared with those of an unmodified ICA 1 analyzer. The unmodified instrument showed a significant difference between measurements in anaerobic venous whole blood, venous plasma, and venous serum, but the modified instrument did not. Statistically significant differences between the two instruments were found for whole blood (magnitude of mean difference magnitude of = 0.053 mmol/L) and for venous serum (0.016 mmol/L), but not for venous plasma. The error of residual liquid junction potential due to blood cells, previously found in the unmodified ICA 1 (salt bridge: KCl, 2.68 mol/kg) was eliminated and independent of the erythrocyte volume fraction in the modified ICA 1 (salt bridge: sodium formate, 4.56 mol/kg). From studies of procedures for measurements of ionized calcium in anaerobically handled samples, we recommend the use of anaerobic whole blood for measuring ionized calcium.

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