The potentiometric determination of hydrogen ion concentrations at higher temperatures

The temperature coefficient of the potential of an electrode can be defined experimentally by reference to (a) the potential of the SHE at the same temperature, (b) the potential of the same electrode at some fixed temperature. These two definitions give rise to the "isothermal" and "thermal" temperature coefficients of electrode potentials. The isothermal coefficient is AS/nF where ~S is the reaction entropy of the "SHE//Electrode" cell. The thermal coefficient is S*/nF where S* is the entropy transported from the hot to the cold heat reservoir by the passage of n faradays of positive electricity through the cell from the cold to the hot electrode (before the onset of thermal diffusion). The entropy S* is divided into an entropy S*E of electrochemical transport which determines the electrode temperature effect, and an entropy S*. of migration transport which determines the thermal liquid junction potential.By assuming that S*~ is negligible in a saturated potassium chloride bridge, we have deduced that the thermal temperature coefficient of the SHE is +0.871 mv/~ [hot electrode (+) terminal] at 25~ The standard ionic entropy S* ~ of electrochemical transport of hydrogen ion is --4.48 cal/deg. Thermal temperature coefficients are computed for calomel, silver chloride, and copper sulfate electrodes and are compared with experiment. Thermal and isothermal temperature coefficients are computed and tabulated for nearly 300 standard electrode potentials.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 132.174.255.116 Downloaded on 2015-03-10 to IP Vol. 106, No. 7 COEFFICIENTS OF ELECTRODE POTENTIALS ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 132.174.255.116 Downloaded on 2015-03-10 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 132.174.255.116 Downloaded on 2015-03-10 to IP

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“…[16] becomes (V,-V~) (Pt/H.. (p.p 1 atm), 0.1M HC1/satd KC1, mv) ~ + 0.64023(t-25) + 0.00064334(t-25) ~[19] …”

mentioning

confidence: 99%

The Temperature Coefficients of Electrode Potentials

deBethune

Licht

Swendeman

1959

J. Electrochem. Soc.

284

154

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“…The irreversible rate of production of Clausius' uncompensated entropy (22,23) from all these fluxes can be expressed by ~ IX1 + JX., -5 EK~X~ >= 0 [2] where the driving forces are X~ ~---dV/T, Xj = dT/T, X~ ----d~JT : R d In a, The two ionic terms are conveniently coalesced to [3] where X~ ~-d~(salt)/T = vR d In a . Equation [2] then becomes : IX~ -5 JXj -5 KXK >= 0 [4] The three fluxes may be expressed by phenomenological equations I : L~,X, -5 LwXj -5 LI~X~ [5] J = LjxX, -5 LjjXj -5 L~XK [6] K = L~rXI + L~jXj -5 LxKX~ [7] where the L's are generalized admittances (reciprocal resistances). By the Onsager reciprocal relations, the conjugate cross-admittances are equal, i.e., L~j ~ Lj~, L~ = LK~ and Lj~ ~ Lxj.…”

Section: General Description Of Thermodynamic Systemmentioning

confidence: 99%

Irreversible Thermodynamics in Electrochemistry

deBethune

1960

J. Electrochem. Soc.

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The Onsager thermodynamics of irreversible processes provides a unified approach to the study of electrolytic systems out of equilibrium, such as concentration cells with transference, the initial and final emf's of thermal cells, and thermal diffusion (Soret effect) of ions. For concentration cells, the method justifies the classical results obtained by Nernst from equilibrium considerations. For nonisothermal systems, the product S*dT is the thermodynamic driving force of a process, where S* is the entropy transported reversibly from the "hot" to the "cold" heat reservoir (in the limiting case of equal temperatures) by the occurrence of a reversible process in the system. The emf of a concentration cell, the initial emf of a thermal cell, and the Soret coefficient, all properties of systems out of equilibrium, are determined, according to the Onsager relations, by the ratios of the reversible fluxes of matter to electricity, of entropy to electricity, and of entropy to matter, respectively, as they occur in systems completely at equilibrium.

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Über die Normalwasserstoffelektrode

Reuther

1943

Zeitschrift für Elektrochemie und angewandte physikalische Chem

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The potentiometric determination of hydrogen ion concentrations at higher temperatures

Cited by 7 publications

References 6 publications

The Temperature Coefficients of Electrode Potentials

The Temperature Coefficients of Electrode Potentials

Irreversible Thermodynamics in Electrochemistry

Über die Normalwasserstoffelektrode

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