Concentration Dependence of Ionic Hydration Numbers

Marcus, Yizhak

doi:10.1021/jp5039255

Cited by 55 publications

(38 citation statements)

References 48 publications

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“…[64,66] The hydrated radius depends on the charge of the central ion and its crystallographic radius; [67] it also depends on the salt concentration, becoming smaller with increasing electrolyte concentration. [68] For ions of the same valence and at the same concentration in solution, such as the ones used in this study, the hydrated radius decreases as the crystallographic radius increases because the charge density is lower for larger ions. As a result, larger ions exhibit a hydration shell composed of a smaller number of water molecules.…”

Section: Role Of Ions and Water In The Doping Behavior Of P(g2t-tt)mentioning

confidence: 85%

Role of the Anion on the Transport and Structure of Organic Mixed Conductors

Cendra

Giovannitti

Savva

et al. 2018

Adv Funct Materials

142

195

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Organic mixed conductors are increasingly employed in electrochemical devices operating in aqueous solutions that leverage simultaneous transport of ions and electrons. Indeed, their mode of operation relies on changing their doping (oxidation) state by the migration of ions to compensate for electronic charges. Nevertheless, the structural and morphological changes that organic mixed conductors experience when ions and water penetrate the material are not fully understood. Through a combination of electrochemical, gravimetric, and structural characterization, the effects of water and anions with a hydrophilic conjugated polymer are elucidated. Using a series of sodium‐ion aqueous salts of varying anion size, hydration shells, and acidity, the links between the nature of the anion and the transport and structural properties of the polymer are systematically studied. Upon doping, ions intercalate in the crystallites, permanently modifying the lattice spacings, and residual water swells the film. The polymer, however, maintains electrochemical reversibility. The performance of electrochemical transistors reveals that doping with larger, less hydrated, anions increases their transconductance but decreases switching speed. This study highlights the complexity of electrolyte‐mixed conductor interactions and advances materials design, emphasizing the coupled role of polymer and electrolyte (solvent and ion) in device performance.

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Section: Role Of Ions and Water In The Doping Behavior Of P(g2t-tt)mentioning

confidence: 85%

Role of the Anion on the Transport and Structure of Organic Mixed Conductors

Cendra

Giovannitti

Savva

et al. 2018

Adv Funct Materials

142

195

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“…[32][33][34] The presence of ions in aqueous solution affects the structure of water by changing the H-bond networks,w hich leads to ions being classified as either kosmotropes (structure makers) or chaotropes (structure breakers). [38,39] Many thermodynamic ands pectroscopic techniques have been used to determine the hydration numberso fe lectrolytes and nonelectrolytes, [40][41][42][43][44][45][46][47][48] the structural details of which have been also studied theoretically by many researchers. Analysis of the thermodynamicso fh ydrogen-bond formation signifiest hat hydrogen-bond making and breaking processes are dominated by enthalpyw ith non-negligible heat capacity effects, as revealed by the temperature dependence of standard molar enthalpies of hydrogen-bond formation andf rom analysiso ft he linear enthalpy-entropy compensation effects.…”

Section: Introductionmentioning

confidence: 99%

“…the form of hydration shells, in aqueous solutionm ainly depends on the charge density of the ions. [38,39] Many thermodynamic ands pectroscopic techniques have been used to determine the hydration numberso fe lectrolytes and nonelectrolytes, [40][41][42][43][44][45][46][47][48] the structural details of which have been also studied theoretically by many researchers. [49][50][51][52][53] Bockris and Saluja estimated the hydration numbers for alkali and alkalinee arth halidesf rom compressibility and observed that the hydration number of alkali metal cationsd ecreased with increasing ion size, whereas divalent cationss howedt he opposite trend to that of monovalent ions, except for the Mg 2 + ion.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Bonding in Liquid Water and in the Hydration Shell of Salts

Dagade

Barge

2016

ChemPhysChem

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A near-IR spectral study on pure water and aqueous salt solutions is used to investigate stoichiometric concentrations of different types of hydrogen-bonded water species in liquid water and in water comprising the hydration shell of salts. Analysis of the thermodynamics of hydrogen-bond formation signifies that hydrogen-bond making and breaking processes are dominated by enthalpy with non-negligible heat capacity effects, as revealed by the temperature dependence of standard molar enthalpies of hydrogen-bond formation and from analysis of the linear enthalpy-entropy compensation effects. A generalized method is proposed for the simultaneous calculation of the spectrum of water in the hydration shell and hydration number of solutes. Resolved spectra of water in the hydration shell of different salts clearly differentiate hydrogen bonding of water in the hydration shell around cations and anions. A comparison of resolved liquid water spectra and resolved hydration-shell spectra of ions highlights that the ordering of absorption frequencies of different kinds of hydrogen-bonded water species is also preserved in the bound state with significant changes in band position, band width, and band intensity because of the polarization of water molecules in the vicinity of ions.

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“…We keep in mind that this is a simple approach based on only one fitting parameter, whereas in reality the situation is much more complex. For example, as the salt concentration increases it is possible that ionic hydration layers overlap [37] and in many salts ion pairs are formed [38]. At present such effects are not included in the electrolyte model used for MC simulations but can indirectly be observed by deviations between experiment and simulations as described below.…”

Section: Resultsmentioning

confidence: 99%

Activity Coefficients of Concentrated Salt Solutions: A Monte Carlo Investigation

Abbas

Ahlberg

2019

J Solution Chem

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Monte Carlo (MC) simulations were used to calculate single ion and mean ionic activity coefficients and water activity in concentrated electrolytes and at elevated temperatures. By using a concentration dependent dielectric constant, the applicability range of the MC method was extended to 3 mol·L −1 or beyond, depending on the salt. The calculated activity coefficients were fitted to experimental data by adjusting only one parameter, i.e., the cation radius. Fitted ionic radii obtained by such a procedure indicate the extent of cationanion interaction in a salt solution. For example, the fitted radii of Li + and Na + in LiClO 3 and NaClO 3 indicate that Li + is strongly hydrated and has a weak interaction with the ClO 3 − ion whereas Na + forms ion pairs and loses its hydration. The single ion activity coefficients for protons and chloride ions in HCl were calculated by MC simulations and compared with experimental values obtained by ion selective electrodes. The calculated single ion activity coefficients for protons and chloride ions are much lower and higher, respectively, than the experimental values. However, the mean activity coefficients of HCl obtained by the MC simulations, ion selective electrodes and vapor pressure measurements are in good agreement. In the case of NaCl and KCl the calculated single ion activity coefficients of Na + , K + , and Cl − are much closer to the values obtained by ion selective electrodes. The results in HCl indicate that the hydrated proton is large and includes the chloride ion within the hydration shell, i.e., the apparent size of the chloride ion is negligible.

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Concentration Dependence of Ionic Hydration Numbers

Cited by 55 publications

References 48 publications

Role of the Anion on the Transport and Structure of Organic Mixed Conductors

Role of the Anion on the Transport and Structure of Organic Mixed Conductors

Hydrogen Bonding in Liquid Water and in the Hydration Shell of Salts

Activity Coefficients of Concentrated Salt Solutions: A Monte Carlo Investigation

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