Entropies of aqueous ions

Breck, W. G.; Lin, Jia-Feng

doi:10.1039/tf9656102223

Cited by 25 publications

(15 citation statements)

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“…7a (18). This is due to the well-known autocomplexation that o'ccurs in zinc halide solutions as indicated by EMF, thermal and Raman spectroscopic experiments (18,23,28). Thus, Shchukarev et al (29) reported widely different TAS values for the formation of ZnBr § ZnBr2, ZnBr3-, and ZnBr42-complex ions.…”

Section: Discussionmentioning

confidence: 94%

“…The latter are quite reliably known for most simple ions from extra-thermodynamic procedures (1,22,23) but the S~ E values, which are not negligible at appreciable concentrations, are not so easily evaluated in a reliable way. Recourse may be had to data calculated from the Debye-H~ickel theory, based on Kielland's work (26), for dilute solutions, but for elevated concentrations where ion size and hydration effects become important (27) in determining T~, the required derivative d In T~/dT is difficult to evaluate.…”

Section: Discussionmentioning

confidence: 98%

“…This value is the sum of the entropy changes due to the ionic entropy, the metal entropy, and the metal electron entropy contributions to the entropy change, aS, of the reversible electrode reaction and also the entropy changes arising as a consequence of ion transport as the cell reaction proceeds, i.e, the so-called Eastman ionic entropies of transport (22)(23), S*. Using known electrochemical and thermodynamic quantities from the literature, Ozeiki et al (2), Tamamushi (3), and Holmes and Joncich (10) have calculated the Peltier heats for the Cu/Cu 2+ and Ag/Ag + single-electrode reactions and compared them with the observed values.…”

Section: Discussionmentioning

confidence: 99%

“…The Eastman entropies of Zn 2+ and Br-ions are 18.8 and 2.5 J K -1 mol-], respectively. The value for the Zn 2+ ion was obtained from the difference between the transportedentropy of hydration and the entropy of hydration itself, Sh -Sh (23). The value for the Br-ion is available from Agar (1).…”

Section: Discussionmentioning

confidence: 99%

“…surface.--The partial molar entropy of Br-ion on the absolute scale is 103.7 J K -~ mo1-1 (23). The ionic activity coefficient for Br-ion at 1.0M concentration, 0.65, was obtained by extrapolating the straight line plot between log CBr-and activity coefficient to 1.0M [Kielland,Ref.…”

Section: Peltier Heat Of the Br-/br2 Reaction At A Platinum Blackmentioning

confidence: 99%

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Electrochemical Calorimetry of the Zinc and Bromine Electrodes in Zinc‐Bromine and Zinc‐Air Batteries

Donepudi

Conway

1984

J. Electrochem. Soc.

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Direct calorimetric measurements are reported on three half-cell reactions of interest in zinc battery thermodynamics: the Zn/Zn 2+ reaction in aqueous Br-solution; the BrJBr-reaction at Pt and the Zn/ZnO-ZnO~-reaction in alkali. An experimental procedure is described for determining the single reaction heats, observable as TAS quantities, in both directions of the above reactions, thus providing a method for eliminating, by difference, the Joule heating effects which are unavoidable in the course of measurements at finite currents. Corrections for entropies of transport are made and discussed. Under certain conditions, where Zn corrosion can occur with evolution of H2, the TAS heat change for that process is also determinable. Some heat changes for overall cell reactions are also determined~ While enthalpy changes for reversible electrochemical reactions can be obtained from EMF measurements and their temperature coefficients by means of the Nernst equation through the Gibbs-Helmholtz relation, such values are necessarily for the overall, two-electrode reaction. Direct calorimetric measurements, subject to some corrections for ionic entropies of transport, can be applied to evaluation of the heat changes that are associated with the electrochemical reactions at the electrodes of a cell. Such directly measurable heats are, however, associated with the "TAS" quantity for the cell reaction, rather than the AH.It is of interest to recall that the actual enthalpy change, AH, for an electrode reaction is not measurable calorimetrically like it would be for a corresponding overall chemical reaction. This is because the AH normally constitutes the main component of the AG value determining the EMF of the cell. From measurements of the latter at various temperatures, ~ can, of course, be determined using a form of the Gibbs-Helmholtz equation.Direct calorimetric measurements made at a suitably designed electrode configuration with an appropriately arranged thermal detection probe, and separated anode and cathode compartments, can also give information on the TZkS quantity for single electrode processes which are of interest in a general way in electrochemical thermodynamics and ionic solution electrochemistry. In some papers (1-3), these TAS quantities have been referred to as electrolytic Peltier heats, and values for several redox reactions at electrodes have been reported (4-5). The first reliable work of this kind was done by Lange and Hesse (6) and Lange and Monheim (7) some years ago, but, for many years since that time up until several years ago, few other papers have appeared on this topic.Renewed interest in electrochemical calorimetry has arisen on account of the importance of measurements of overall and component heat changes in battery processes. Such measurements are essential for understanding the thermochemistry of battery reactions and in assessing practical energy efficiencies as well as evaluating heat changes associated with various contributions to irreversibility in battery charge and discharge cycle...

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Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Peltier Heat Of the Br-/br2 Reaction At A Platinum Blackmentioning

confidence: 99%

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Electrochemical Calorimetry of the Zinc and Bromine Electrodes in Zinc‐Bromine and Zinc‐Air Batteries

Donepudi

Conway

1984

J. Electrochem. Soc.

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Berechnung von freien Hydratationsenthalpien und Koordinationszahlen für Kationen aus leicht zugänglichen Parametern

Morf

Simon

1971

Helvetica Chimica Acta

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1. Einleitung . -In1 Ralimen von Untersuchungen an ioncnselektiven Systenien ill ist die Kenntnis der freien Solvatationsenthalpien von Ionen fur eine Reilie von elektrisch neutralen Liganden notwendig geworden. Da sich derartige Behandlungen der Solvatation bislier auf nur wenige nichtwasserige Losungsmittel wie z. B. Formamid [2] beschrankten, wurde ein Modell geschaffen, welches allgeniein die Hcrechnung der freien Solvatationsenthalpien und Koordinationszahlen von Kationen aus ciner besonders kleinen Zahl bekannter Daten erinoglicht. In der vorliegenden Arbeit wird einerseits uber ein derartiges Modell berichtet und andererseits wcrden Resultate diskutiert, die damit fur die Hydratation als besonders ausgiebig untcrsucliteni Fall dcr Solvatation erzielt wurden. Die bisher bekannten Theorien zur Bereclinung freier Hydratationscntlialpicn von Kationen lasseri sich im wesentlichen in zwei Gruppen aufteilen. Die empirischen Korrelationen, welche aus den1 Modell von BOWL 131 rnit Rehandlung des Losungs-

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Proton Transfer in Solution

Erdey-Grúz¹,

Lengyel²

1977

Modern Aspects of Electrochemistry

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Entropies of aqueous ions

Cited by 25 publications

References 0 publications

Electrochemical Calorimetry of the Zinc and Bromine Electrodes in Zinc‐Bromine and Zinc‐Air Batteries

Electrochemical Calorimetry of the Zinc and Bromine Electrodes in Zinc‐Bromine and Zinc‐Air Batteries

Berechnung von freien Hydratationsenthalpien und Koordinationszahlen für Kationen aus leicht zugänglichen Parametern

Proton Transfer in Solution

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