scholarly journals Thermochemical Measurements of Alkali Cation Association to Hexatantalate

2018 ◽  
Author(s):  
Dylan Sures ◽  
G. P. Nagabhushana ◽  
Alexandra Navrotsky ◽  
May Nyman
Keyword(s):  
Concentration Dependence ◽  
Ion Association ◽  
Aqueous Solubility ◽  
Ion Pairing ◽  
Lattice Energy ◽  
Enthalpies Of Formation ◽  
Neat Water ◽  
Dissolution Enthalpies ◽  
Complex Relationships ◽  
Alkali Salts

Ion association is an important process in aqueous dissolution, precipitation, and crystallization of ionic inorganic, organic, and biological materials. Polyoxometalates (POMs) are good model compounds for understanding the complex relationships between lattice energy, ion-pairing in solution, and salt solubility. Here we perform calorimetric measurements to elucidate trends in cluster stability, lattice energy, and ion-pairing behavior studies of simple hexatantalate salts in neat water, parent hydroxide solutions, and molybdate melts, extending previous studies on the isostructural hexaniobates. High temperature calorimetry of alkali salts of hexatantalate reveals that the enthalpies of formation from oxides of the K, Rb, and Cs salts are more similar to each other than they are for their niobate analogues and that the tantalate cluster is energetically less stable than hexaniobate. Aqueous dissolution calorimetry reveals that the cesium salt of hexatantalate has a similar concentration dependence on its dissolution enthalpy to that of hexaniobate. However, unlike rubidium hexaniobate, rubidium hexatantalate also exhibits increased concentration dependence, indicating that hextantalate can undergo increased ion-pairing with alkali salts other than cesium, despite the dilute environments studied. Dissolution enthalpies of POM salts in the parent alkali hydroxides shows that protonation of clusters stabilizes lattices even more than the strongly associating heavy alkalis do. Additionally, neither weak nor strong lattice ion associations necessarily correlates with respectively high or low aqueous solubility. These studies illuminate the importance of considering ion-pairing among the interrelated processes in the aqueous dissolution of ionic salts, that can be extended to serving as a model of cation association to metal oxide surfaces.

scholarly journals Thermochemical Measurements of Alkali Cation Association to Hexatantalate

2018 ◽  
Author(s):  
Dylan J. Sures ◽  
G. P. Nagabhushana ◽  
Alexandra Navrotsky ◽  
May Nyman
Keyword(s):  
Concentration Dependence ◽  
Ion Association ◽  
Aqueous Solubility ◽  
Ion Pairing ◽  
Lattice Energy ◽  
Enthalpies Of Formation ◽  
Alkali Cations ◽  
Neat Water ◽  
Complex Relationships ◽  
Alkali Salts

Ion association is an important process in aqueous dissolution, precipitation, and~crystallization of ionic inorganic, organic, and biological materials. Polyoxometalates (POMs) are good model compounds for understanding the complex relationships between lattice energy, ion-pairing in solution, and salt solubility. Here we perform calorimetric measurements to elucidate trends in cluster stability, lattice energy, and ion-pairing behavior studies of simple hexatantalate salts in neat water, parent hydroxide solutions, and molybdate melts, extending previous studies on the isostructural hexaniobates. High temperature calorimetry of alkali salts of hexatantalate reveals that the enthalpies of formation from oxides of the K, Rb, and Cs salts are more similar to each other than they are for their niobate analogues and that the tantalate cluster is energetically less stable than hexaniobate. Aqueous dissolution calorimetry reveals that the cesium salt of hexatantalate has a similar concentration dependence on its dissolution enthalpy to that of hexaniobate. However, unlike~rubidium hexaniobate, rubidium hexatantalate also exhibits increased concentration dependence, indicating that hextantalate can undergo increased ion-pairing with alkali salts other than cesium, despite the dilute environments studied. Dissolution enthalpies of POM salts in the parent alkali hydroxides shows that protonation of clusters stabilizes lattices even more than the strongly associating heavy alkali cations do. Additionally, neither weak nor strong lattice ion associations necessarily correlates with respectively high or low aqueous solubility. These studies illuminate the importance of considering ion-pairing among the interrelated processes in the aqueous dissolution of ionic salts that can be extended to serving as a model of cation association to metal oxide surfaces.

scholarly journals Thermochemical Measurements of Alkali Cation Association to Hexatantalate

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2441 ◽  
Author(s):  
Dylan Sures ◽  
G. Nagabhushana ◽  
Alexandra Navrotsky ◽  
May Nyman
Keyword(s):  
Concentration Dependence ◽  
Ion Association ◽  
Aqueous Solubility ◽  
Ion Pairing ◽  
Lattice Energy ◽  
Enthalpies Of Formation ◽  
Alkali Cations ◽  
Neat Water ◽  
Complex Relationships ◽  
Alkali Salts

Ion association is an important process in aqueous dissolution, precipitation, and crystallization of ionic inorganic, organic, and biological materials. Polyoxometalates (POMs) are good model compounds for understanding the complex relationships between lattice energy, ion-pairing in solution, and salt solubility. Here we perform calorimetric measurements to elucidate trends in cluster stability, lattice energy, and ion-pairing behavior studies of simple hexatantalate salts in neat water, parent hydroxide solutions, and molybdate melts, extending previous studies on the isostructural hexaniobates. High temperature calorimetry of alkali salts of hexatantalate reveals that the enthalpies of formation from oxides of the K, Rb, and Cs salts are more similar to each other than they are for their niobate analogues and that the tantalate cluster is energetically less stable than hexaniobate. Aqueous dissolution calorimetry reveals that the cesium salt of hexatantalate has a similar concentration dependence on its dissolution enthalpy to that of hexaniobate. However, unlike rubidium hexaniobate, rubidium hexatantalate also exhibits increased concentration dependence, indicating that hextantalate can undergo increased ion-pairing with alkali salts other than cesium, despite the dilute environments studied. Dissolution enthalpies of POM salts in the parent alkali hydroxides shows that protonation of clusters stabilizes lattices even more than the strongly associating heavy alkali cations do. Additionally, neither weak nor strong lattice ion associations necessarily correlates with respectively high or low aqueous solubility. These studies illuminate the importance of considering ion-pairing among the interrelated processes in the aqueous dissolution of ionic salts that can be extended to serving as a model of cation association to metal oxide surfaces.

Crystal structure and lattice energetics of 10-methylacridinium halides

2000 ◽  
Vol 53 (8) ◽  
pp. 627 ◽  
Author(s):  
Piotr Storoniak ◽  
Karol Krzyminski ◽  
Pawel Dokurno ◽  
Antoni Konitz ◽  
Jerzy Blazejowski
Keyword(s):  
Crystal Lattice ◽  
Lattice Energy ◽  
Enthalpies Of Formation ◽  
Triclinic Space Group ◽  
X Ray ◽  
Molecular Arrangement ◽  
Van Der Waals Contacts ◽  
Chloride Monohydrate ◽  
Insight Into

The crystal structures of 10-methylacridinium chloride monohydrate, bromide monohydrate and iodide were determined by X-ray analysis. The compounds crystallize in the triclinic space group, P¯1, with 2 molecules in the unit cell. The molecular arrangement in the crystals revealed that hydrogen bonds (in hydrates) and van der Waals contacts play a significant part in intermolecular interactions. To discover their nature, contributions to the crystal lattice energy arising from electrostatic (the most important since the compounds form ionic crystals), dispersive and repulsive interactions were calculated. Enthalpies of formation of the salts, their stability and susceptibility to decomposition could be predicted from a combination of crystal lattice energies with values of other thermochemical characteristics obtained theoretically or taken from the literature. The role of water in the stabilization of the crystal lattice of the hydrates is also explained. The information gathered has given an insight into the features and behaviour of compounds which can be regarded as models of a large group of aromatic quaternary nitrogen salts.

scholarly journals Drawbacks of Low Lattice Energy Ammonium Salts for Ion-Conducting Polymer Electrolyte Preparation: Structural, Morphological and Electrical Characteristics of CS:PEO:NH4BF4-Based Polymer Blend Electrolytes

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1885 ◽  
Author(s):  
Mohamad A. Brza ◽  
Shujahadeen B. Aziz ◽  
Muaffaq M. Nofal ◽  
Salah R. Saeed ◽  
Shakhawan Al-Zangana ◽  
...  
Keyword(s):  
Polymer Electrolyte ◽  
Polymer Blend ◽  
Salt Concentration ◽  
Ion Association ◽  
Lattice Energy ◽  
High Salt ◽  
Ammonium Salts ◽  
High Salt Concentration ◽  
Electrochemical Device ◽  
Device Applications

In the present work it was shown that low lattice energy ammonium salts are not favorable for polymer electrolyte preparation for electrochemical device applications. Polymer blend electrolytes based on chitosan:poly(ethylene oxide) (CS:PEO) incorporated with various amounts of low lattice energy NH4BF4ammonium salt have been prepared using the solution cast technique. Both structural and morphological studies were carried out to understand the phenomenon of ion association. Sharp peaks appeared in X-ray diffraction (XRD) spectra of the samples with high salt concentration. The degree of crystallinity increased from 8.52 to 65.84 as the salt concentration increased up to 40 wt.%. These are correlated to the leakage of the associated anions and cations of the salt to the surface of the polymer. The structural behaviors were further confirmed by morphological study. The morphological results revealed the large-sized protruded salts at high salt concentration. Based on lattice energy of salts, the phenomena of salt leakage were interpreted. Ammonium salts with lattice energy lower than 600 kJ/mol are not preferred for polymer electrolyte preparation due to the significant tendency of ion association among cations and anions. Electrical impedance spectroscopy was used to estimate the conductivity of the samples. It was found that the bulk resistance increased from 1.1 × 104 ohm to 0.7 × 105 ohm when the salt concentration raised from 20 wt.% to 40 wt.%, respectively; due to the association of cations and anions. The low value of direct current (DC) conductivity (7.93 × 10−7 S/cm) addressed the non-suitability of the electrolytes for electrochemical device applications. The calculated values of the capacitance over the interfaces of electrodes-electrolytes (C2) were found to drop from 1.32 × 10−6 F to 3.13 × 10−7 F with increasing salt concentration. The large values of dielectric constant at low frequencies are correlated to the electrode polarization phenomena while their decrements with rising frequency are attributed to the lag of ion polarization in respect of the fast orientation of the applied alternating current (AC) field. The imaginary part of the electric modulus shows obvious peaks known as conduction relaxation peaks.

Concentration Dependence of Ion Pairing in Imidazolium‐Based Ionic Liquid Solutions

ChemPhysChem ◽  
2019 ◽  
Vol 20 (3) ◽  
pp. 482-488 ◽  
Author(s):  
Seoncheol Cha ◽  
Minho Lee ◽  
Doseok Kim
Keyword(s):  
Ionic Liquid ◽  
Concentration Dependence ◽  
Ion Pairing ◽  
Liquid Solutions

Nitrate Selectivity of Ion-Exchange Resins and of Their Model Compounds. I. Conductance Measurements on Benzyltrialkylammonium Salts

1990 ◽  
Vol 43 (12) ◽  
pp. 1983
Author(s):  
BJ Steel ◽  
AS Kayaalp ◽  
T Kurucsev ◽  
AD Ward ◽  
MB Jackson
Keyword(s):  
Aqueous Solution ◽  
Ion Exchange ◽  
Concentration Dependence ◽  
Ion Pairing ◽  
Association Constants ◽  
Ion Exchange Resins ◽  
Methyl Ethyl ◽  
Model Compounds ◽  
Sulfate Salts ◽  
Exchange Resins

The concentration dependence of the conductance in aqueous solution of a series of benzyltrialkylammonium chlorides, nitrates and sulfates was measured. The n-alkyl substituents in this series were methyl, ethyl, propyl , butyl and pentyl. The conductances of the chlorides, nitrates and sulfates fit satisfactorily the electrostatic ion pairing models relevant to 1 : 1 and 1 : 2 electrolytes. The extent of ion pairing is small in all the solutions studied but consistently larger for nitrates and sulfates compared with chlorides. The dependence of the association constants on the alkyl substitutents shows different trends for the monovalent anions compared with the sulfate salts.

Sign in / Sign up

Export Citation Format

Share Document